how much completion before you paint?

Hello folks, I'm just curious as to what point you reach before you airbrush your models' hull or body?

I am working on a couple models... a Willys jeep by Hasegawa, and a Chevelle by amt.

 obviously with the Velle Iam going to paint the body seperate, but with the Willys I am trying to decide. should I complete as much of the body as I can.. to include  grab handles, etc.   or should t be a paint everything olive drab, go back and paint smaller parts of different colors.. i.e. the canvas cusions and the tool handles... then do final assembly?

thanks for the replies to obvious new guy concerns.

Crash