Nessonite, you have drawing skill - I particularly like the kitchen chair picture - so that will put you ahead in 3D work. It's alot of trial and error mostly and can seem very complex at first because there are so many variables to change.
The proper way is to start with simple scenes and change poses, lighting, camera angle and focal length and read the manual plus the great tutorials on Renderosity.
Of course I did none of these, jumped off a cliff and floundered around for ages before getting anywhere. Now I can get close to what I'm after but it hardly ever follows the original plan - something else crops up.
What's interesting is the programmer who wrote Poser actually started it as a frustrated artist trying to draw simple poses with a lay figure. He couldn't get the poses he wanted from the real thing so wrote a program to do it on the screen.
If you have a look atamazon city, this guy really knows his 3D art. Too bad he's not into tickling.