Tempest,
How you start is pretty much determined by where you what to end up. Are you just concentrating on the interior? Will you be painting the cab interior? If so, you may want to save the rubber and other final touches for last. Strip out the interior and start back in reverse order.
Treat the rust, refinish the metal, take care of the dash & wiring, then start reinstalling the carpet/mat, seats, door panels, headliner, glass and window rubber, trim, done!
Just off the top of my head. Others may have better ideas (likely

)
Good luck!
John