mathman, i think a good sense of balance is needed with any good scene. just the way things/characters are arranged on the set. if you skim through the galleries look at just the scene setup, don't get lost in what the picture is saying to you, look at it analytically...and you will quickly see if a scene seems to fit, or flow, and one that doesn't. this should become fairly straight forwad after a while.

also, know how to create a standard 3 light setup, like they use for movies or photoshoots (google+3lightsetup=info!). poser more or less creates this for you automatically. a key light, a fill light and a back light. some say to put your backlight opposite your key light, poser does that too. in my opinion lights are much more of an artistic thing than say the scene setup. you should already have a good idea of what you want ahead of time. so here is what i do and it's worked very well:

i make all colors white, i turn all lights "off", i turn light 1 "on" to say 1/3rd to 1/2 and postion it where you think you want your main source of light to be coming from, now watching your figure, and how the light is reacting/bouncing off the body, fine tune the light positioning by what shading/shadowing "looks best" or more dramatic, turn that light "off"...now same thing with light 2 which will be backing up light 1 in a support role (positioning wise) and finally our backlight, light 3. then just start bringing them "on" one at a time and doing "quickie" renders to monitor progress. be careful with the intensity levels, you don't want to wash stuff out.

anyways, sorry to babble...hope this helps

Comitted to excellence through art.