The last images you posted definitely improve on the balance of the image IE: things are quished to one side.

However while you do have shadows in your image, the thing that strikes me is that there is no "depth": things seem to be floating on the walls and floor and table tops.

I think you need to use some ambient occlusion in order to get the stuff to look like it's sitting on or hanging against a surface . See this thread:

http://www.renderosity.com/mod/forumpro/showthread.php?message_id=3099295

I used it in my "Unforgiven II" image for the coffin dirt as well as for the coffin and things sitting on the floor in order to give some depth/shadow and make it look like they were actually casting some shadows where they were sitting.

http://www.renderosity.com/mod/gallery/index.php?image_id=1548180

TBH you have only been using the program for less than 2 months and intensely for a couple weeks.  Poser has a large learning curve. Anyone can put stuff into it and render it out, but so far as "professional" quality, that only comes with time and  lots and lots of experience.

I strongly suggest that you work to learn lights as well as the material room.

Here is a link to a list of bookmarks related to the material room.  At the top are some very newbie type tutorials that cover what each node does.  And the rest is catagorized according to task.  Scroll through because there have been updates.

http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2722867

Here is an old bookmark relating to lighting tutorials and links about lighting. Some are Poser, some are post work.

http://market.renderosity.com/mod/forumpro/showthread.php?thread_id=2662390

The ones I strongly recommend are the following:

Olivier's Making of a pomo pic
Castle Poser Tutorials
Poser 6 IBL Ins and outs by Olivier
A little tutorial about lighting by Olivier
Tutorial: GEL MAPS by Olivier

Lighting is one of the most important aspects of an image and it can either make or break your image.

"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