Whiterook,
A lot of us like to build and paint in subassemblies. A few like to build everything first, and a few like to paint first.
It all depends on the vehicle for me, whether it's open top or not being the major factor. If it is, I'll build the gun assembly, the interior walls, and the suspension. Then paint them all before attaching permanantly so I can get good coverage. Closed vehicles you can pretty much assemble most of it before painting. I also like to paint the bogies before I attach them...especially with overlapping road wheels like a Tiger or Panther. I usually like to leave tools and such off the model until I have the base colors sprayed, but not always it just depends on the colors and my mood I guess.