Well,

I usually come up with some mad idea for a render and then start thinking about how the heck I'm actually going to pull it off.
If it involves people then it's off to check the runtimes to see if I have appropriate clothes etc. (assuming they are wearing any that is :) )

Then decide if I need to make any props etc. and if so then get references etc. and fire up Max/ZBrush as appropriate.

Set up the peeps in Poser with the clothes, morphs and textures etc. then decide if it's going to be a Vue or Max render (Vue gets saved as a PZ3 file, Max gets exported as .obj)

Build the scene and decide on the lighting.  I'll usually have a pretty good idea of how I want to light whatever it is so it's a case of deciding on which type of light, volumetrics, shadow settings etc and then start test rendering and tweaking.

Save as a PNG file and usually save out a ZDepth map as well just in case (if I'm using Max, I might do a bunch of passes; diffuse, spec, reflection, maybe shadow)

then bung the whole lot into either Photoshop or Composite (used to be Toxic - comes free with Max 2011) and put it all together.

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