The following is a great deal of information to process, but it's only meant as a guide and not to be memorized.  I have it broken up into sections. My advice is to read it through once, print it out and keep the print out next to your computer for reference as needed.

Here is an essay of information that I have been compiling which is geared to the brand new user. **It has links for free characters, tips on clothing, file organization, newbie tutorials etc.
**
V3, M3  and Aiko are free.  3D Models Pack  Free from Daz at Download.com

You just need the morphs packages to change their shape. 

A picture to show you the file structure of a Poser Runtime can be found here:

http://www.daz3d.com/support/faq/index.php?id=94

Basically, what it boils down to in a nutshell:

If you are looking for a Character or a piece of clothing/shoes, in Poser you will find them in libraries/character. These files have the extension cr2 (uncompressed) and c2z (compressed)

If you are looking for hair, you will find them in either library/character/hair OR library/hair

If you are looking for character texture addons, hair textures, clothing textures, you will find them in library/poses. These files have the extension pz2 (uncompressed) and p2z (compressed). Sometimes on the rare occasion, a merchant will package their textures so that they go into the "Camera" folder (.cm2 files). If that is the case then you can either apply them from there, or do what I do and change the file extension to .pz2

If you are looking for props, they are located in library/props. These files have the extension pp2 (uncompressed) and ppz (compressed)

Sometimes you will find clothing and hair or shoes in library/props too, depending on whether the item is actually created and saved as a figure, or it was created and saved as a prop.

Figure (cr2) items like hair and clothing are "conformed". Figure items like wings are "parented"

Props are parented. Some props that are made for a specific figure will seem to go where they are supposed to and "stick" without you having to do anything. Those are called "smart props". You can use those on other figures, but you have to use the XYZ trans dials to place it where it belongs on the different figure. Then you need to parent the item to that new figure's body part.

If you are just starting, it's best to get started on the right foot. DO NOT just install files into the runtime! That will only lead to frustration because you won't be able to find anything, and not all files are packaged equally and land up all over the place.

Here is a link to a tutorial on using multiple runtimes.

http://forum.daz3d.com/viewtopic.php?t=9060&start=0

http://www.drgeep.com/p5/run/run.htm

Another tip is to never just unzip or install anything directly to your runtime. Always unzip or install to a separate folder. Then browse through the folder to have a look at the structure of where things are going and make sure that it's in "proper runtime structure" so that when you move it to the runtime, they get into the proper folders.

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Once you get your files installed, the next thing you want to do is to start making things :)

Here are some great newbie tutorials that will get you through the bare basics. They are for Poser 5, but it is still the same in newer versions:

http://trekkiegrrrl.dk/tut1.htm

http://www.poserguide.nimprodaction.com/issues/issue2/cover.htm

http://www.poserguide.nimprodaction.com/issues/issue3/cover.htm

http://www.poserguide.nimprodaction.com/

http://www.canary3d.com/tutorial/3d-intro.htm

http://www.ebonshire.net/tut-posb/index.php

http://www.cooltuna.com/poser/poser-tutorials.html

Dr. Geep Studios ( Basic to Advanced Tutorials. Periodically offers free classes for Poser)

http://www.anniescorner.net/posertuts/GettingStartedinPoser5.htm

Getting Started in Poser

Video Tutorials

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If you don't have the Daz  V3 or the V4 figure, you should pick one or both. I'd personally suggest that you go with the V3 one as it's been around for years and there is a TON of freebies around for her, as well as a TON of stuff in the various Poser stores.  It will be a couple of years before V4 catches up with clothing content and stuff, especially FREE stuff  and  V3 stuff won't work on V4 because they are different figures. There are work arounds to getting clothing from a figure to fit another figure. I've included information on that further down. 

Victoria 3

3D Models Pack  Free from Daz at Download.com

Victoria 4

But if you want to change the look of her face and body, or use any of the available character addon packages, you need to buy the head and body morphs.

The V3 head and body morphs are here:

http://www.daz3d.com/shop.php?op=itemdetails&item=3008

There is also "Michael 3".  He is available free at the link above at download.com.  Again, like Vicky, you need the head and body morphs to change the shape of his head and body. Those can be found here:

http://www.daz3d.com/shop.php?op=itemdetails&item=3009

If you have both figures, you can get both of their head and body morphs in one package, here:

http://www.daz3d.com/shop.php?op=itemdetails&item=3010

NOTE:  You can use the textures from the character addon packages without having the head/body morphs. 

If you want to change the look of the head/body and have the head/body morphs, do the following:

Install the head and body morphs. 

Locate the morphs you want to use in the "Poses" folder.

Find the set of morphs you want to inject IE:  Full Body, Full Head.... or just certain parts. 

Left  click the picture

Click the Single Checkmark at the bottom of the page.

Go to your Parameter Dials and start turning dials.  (make sure that you have the part of the body you want to adjust as the active one IE:  Morphing the ears, make sure you have the had selected.

Also, you can find many, many free morphs and textures for Vicky, and Aiko, and some even for David and Michael.  So you don't have to turn any dials if you don't want to.  Here are a couple links to get you started.

http://www.renderosity.com/mod/freestuff/index.php?user_id=55140

http://www.renderosity.com/mod/freestuff/index.php?user_id=178490

http://www.renderosity.com/mod/freestuff/index.php?user_id=105158

Using ready made character addons is pretty easy.   You need to have the figure and it's head and body morph packages installed.

Load up the figure IE: Vicky

Go to the Poses folder, and instead of looking for your morphs from the packages, look for th character you want to use.  Left click the image that has INJ, click the SINGLE checkmark at the bottom and the morphs for that character's look is injected into your figure.  No dial turning necessary.  Of course if you want to tweak the settings you can, but that's not mandatory.

Next locate the textures (if the package has some). They will be usually in the same library menu as your INJ that you used.   Left click the image for the texture and use the SINGLE checkmark to apply it.  If you don't like that texture, apply another one overtop. 

You can even use a texture from another package.  IE: Morphs from package A  and textures from package C.  Or morphs from packag A, texture from package C, eyes from package D, lips from package E.  the combinations are endless :)  If the packages have their head morphs seprate from the body ones, you can mix and match morphs too. IE: body morphs from package A with head morph from package D.  That allows for even more versatility.

There are lots of sites out there that has free V3 character addons, and some that have for Aiko, Michael and even David.

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Hair, clothing and textures are all figure/item specific, which means:

Michael 3.0 needs hair and clothing and textures made for Michael 3.0
Victoria 4.0 needs hair and clothing and textures made for Victoria 4.0
Victoria 3.0 needs hair and clothing and textures made for Victoria 3.0
Victoria 2.0 needs hair and clothing and textures made for Victoria 2.0
Aiko needs hair and clothing and textures made for her.

Like figures, a texture made for one hair style can only be used on that hair style.

Clothing is also specific when it comes to textures. A texture for a pair of pants, won't fit all pants... just the pants that it was made to fit. Same with all clothing items.

Sometimes you can manage to  clothing item to fit another figure by tweaking of dials and increasing or decreasing the scale percent, but that doesn't always work. Sometimes a clothing item for Victoria 2 will fit Victoria 3, but their joints are different so posing a figure wearing clothing not made for it specifically will be hard.

Some figures can share items more easily than others, here is a link that will help sort that out:
http://market.renderosity.com/mod/forumpro/showthread.php?message_id=2682279

There are 3 types of clothing:

Dynamic:  This is clothing that you use inside the Cloth room. It takes longer to work with and there is a bit of a learning curve, but it's not too bad, but the results are more appealing in that the clothing actually looks more natural instead of "posed and stiff".  I have included information about this type of clothing further down.

Confroming- Non Morphing:  This is clothing that you conform to a figure. The clothing is made to fit the base figure.  If you change the shape of the figure you will also have to refit the clothing, which isn't always easy if there aren't any corresponding body morphs in the clothing.  Plus posing a character in positions where they are not nearly upright is difficult.  But many prefer this type of clothing over dynamic.

Conforming-Morphing: This is the same as conforming-non morphing, only there are morph dials that you can turn that have corresponding body morphs for easier fitting.  This is the preferred type of conforming clothing because it's easier to fit.

Using a clothing item on a figure that it is meant to be used on, after you have added morphs and adjusted the shape of the body,  can be problematic because the clothes are made for the default figure shape and not the new morphed up shape. So the clothing no longer fits and you get parts of the body showing through the clothing after you add morphs and change the shape of the body.

There are programs that can help fit clothing from one figure to another, or even from the same figure to one that has been "morphed up" using their morph packages.

The Tailor, which can be bought here:
http://www.daz3d.com/shop.php?op=itemdetails&item=677

Wardrobe Wizard (I use this one and it's great). It can be purchased from PhilC's site here:
http://www.philc.net/WardrobeWizard.htm

Clothes Converter, which can be bought here:
http://www.daz3d.com/shop.php?op=itemdetails&item=3069&cat=131

Things like hair can be used across all figures just by tweaking the scaling and trans dials and then parenting the hair to the figure.

Poses are something else that can be used across most human-like figures with just a bit of tweaking to dig out a hand, or fix a shoulder.

Dynamic Clothing (more information):

A nice thing about dynamic clothing is that you can easily use clothing on various figures.Here are some tutorials on how to use dynamic clothing in the cloth room:

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2665209

http://www.philc.net/CC_sampleVideo.htm

http://www.poserfashion.net/howvic3dress1.htm

http://drgeep.com/p5/cr/cr.htm

Here are some links to some great FREE dynamic clothing:

http://www.renderosity.com/mod/freestuff/index.php?username=mapps

http://www.renderosity.com/mod/freestuff/index.php?username=svdl

http://www.renderosity.com/mod/freestuff/index.php?username=Stegy

http://www.renderosity.com/mod/freestuff/index.php?username=carib98

http://www.renderosity.com/mod/freestuff/index.php?username=teyikung

It's also possible to make conforming clothing into dynamic clothing:

http://www.renderosity.com/mod/tutorial/index.php?tutorial_id=868

And it's possible to take a conforming outfit and work with it in the cloth room so that parts of it act dynamic.

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2517340&page=1

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi