I know one could tell me "dig more" but in fact I have and it's a bit all over the place... let's say I want to learn how to create expressions for V4. What would be the tutorial you guys would recommend me? Cheers :)

I am not aware of any tutorials on the subject of expressions, if there is I would certainly be interested.  At the moment I tend to use a few methods, the first is a mirror, in that I try to mimic the expression I am want to achieve and see what parts of the face move or are involved.  Another way is I try and find an example of the expression I want on the internet and try and match the face again, if I can find a model or celebrity with a blank type look and the expression I want, I look for the differences.  If you don't mind spending a little bit of money sites like 3d.sk have human reference photos that a vest selection in facial expressions.  

Last method I use is to purchase some expressions and pick the closest to what I want and tweak that.  I have to do that with all purchased expressions anyway as the character morphs affect how the expressions look on my character.  There also used to be a program where you selected the expression you wanted, such as half smile and that was then applied to V4, not sure it is still available but it only used the expression morphs in V4 so playing with them and see what the do could be a good starting point.

simontemplar

Go to Poser By Design and look at the A3 Expressions Secret Video (on front page). Instead of using the Pins just use the morph tool in a similar manner on V4.   If you want to use the exact same technique as shown in the video then you'll need to inject the A4 morphs into V4. Your character will still look like V4 but now the entire face will move as you create the expression. 

The key to this method is locating where to place the pins on face to hold down certain parts of the face as you use the morph tool.

I would agree with hornet3d.  I haven't seen any facial expression tutorials either and you have, at least, two methods to approach the workflow.  Expression morphs can be generated by altering the mesh in a 3rd party modelling program which can grant you greater control over how slight or exaggerated the expression can be featured.  This may takes hours of practice to get it just right.  However, if the vertices are drastically changed, the target morph will be rejected upon import.

The other method is using dial spinning to obtain the desired expressions.  The only pitfall is you are constrained to the maximum/minimum limitations of the morph before features become distorted.  

Looking at yourself in the mirror making faces will give you a basic understanding on how facial muscles interact.  If you are primarily interested in still photo expressions, I would recommend studying the photographs of photojournalists which capture a wide range human emotions and expressions.

simontemplar

I did a quick sample of the method using V4 with the Aiko4 injections.  Both expressions took about 10 seconds to make. You can combine the technique and dials, so don't think of it as using one method over the other.  Using both is an option.  The first expression (image on left) was done using the morph tool technique and the image on the right uses a combination of the morph tool technique and a single change in the parameter dials.

A few years ago my partner won the Christmas writing contest here at Rendo, and we split the winnings ... I bought a book that really could be your answer.  You still need to do the work of making the expressions in Poser ... but for expressions:

Facial Expressions – A Visual Reference for Artists

Facial Expressions is a series of photographic reference books for artists of all styles. The first in the series, featuring adults ages 20-83, includes over 3,200 photos of 50 models. Other galleries included feature kissing, phonemes, hats and headgear, skull and more.

Amazon Best-Seller since its release.

Artists from around the world supplied artwork inspired by the photos.

Galleries include:

• Skull Gallery
• Expressions Gallery
• Sequential-Expressions Gallery
• Kissing Gallery
• Phonemes Gallery
• Hats & Headgear Gallery

Photo Gallery

Free sample Phonemes page, not included in book (as seen in Animation Magazine).

Jason Meyer – Age 24

Found object sculpture by Mike Conrad and digital painting by Brad Vancata inspired by photos in this book.

Illustrations by Steve Sawran and Travis Blaise inspired from photos in this book.

Copyright 2005 Willie Castro

Sample page from Hats & Headgear Gallery.

Sample page from Kissing Gallery.

Profile phoneme sample not included in book (as seen in Animation Magazine).

Found object sculpture by Mike Conrad and digital painting by Brad Vancata inspired by photos in this book.

“The most amazingly diverse collection I’ve ever seen.”
Bud Plant
Bud Plant Comic Art

Profile sample from Phonemes Gallery. Book contains shots of 4 models’ phonemes.

Front view of phonemes samples.