Hi trooper6. I will try to be as breef as possible, even if discussing 3D techniques may be considered on topic here. It's only that, when we talk about 3D in this forum, I feel like a lot of red bloodshot eyes are looking at me in anger

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First, clothes: there are 3 kind of clothes you can use: simple props (like a bikini, for example) that are just parented to the figure, conforming clothes that have "bones" similar to the human figure (those are the ones which deform badly in some poses) and dynamic clothes, which simulate real cloth, but I never use them because they make my seven year old machine crawl and moan. What makes clothing looks better is the resolution of the model. DAZ Studio lets you increase the model resolution, if needed. The quality of the original model is important, too. The clothes of the running man in my pictures (Luthbell's "Eldritch Seeker") are beautifully done by the original modeller, but the suit of the man that is in the background on the first picture is terrible (that's why I put him in the background

). Another thing that helps clothes look better is surface properties adjust and proper lighting and shadows. Light is the most important element in any 3D render. If the model is what I want, but it isn't good (I have to use a lot of free models created by amateurs like me), I try increasing it's resolution and doing some touch up manually in Photoshop. If it's totally hopeless, I render the model half nude and draw the clothes over him.
Facial expressions: body language and facial expressions were more difficult to do in my Toire No Hanako days, when I had to adjust each face element with patience. These days, it has become easier. In DAZ Studio, use any selection tool and click on the model's head. Go to the parameters tab. Click on "pose controls", then on "head", then on "expressions". You will see a list of basic facial expressions you can apply to your model. You can refine them, or mix and match expressions. Or you can click on each face element on the face cathegory and adjust them one by one. Again, adjusting surface properties (especially in the eyes) light and shadow and camera angles can make your figure look more expressive. If everything is not enough for what you want, Photoshop (or Gimp) tools are there to help. 3D is only one more tool.