I usually build like color sub-assemblies before painting anything (engine/trans with painted valve covers, manifolds, fuel pumps, oil filters, etc.) or (chassis, suspension, subframes, mounts - sometimes radiator core supports) (bodies with bumpers, front grille areas and rear tailpans)
Then I can paint it all at once and minimize messy glue joints for the major parts. I find that detail painting the small glued-on parts easier than trying to glue them on after they've been painted.