I think everyone builds differently, and there's really no sure-fire method that works better than the others.
When I build aircraft, I paint, detail, and weather the cockpit before the fuselage halves are joined. This includes PE seatbelts too. I, like everyone else, generally stuff wet tissue into the cockpit, although I typically add masking tape to the edges to completely cover the cockpit opening. If I'm building a serious, hardcore model, I'll get canopy masks and spray the frames. If I'm building for fun, I'll hand-paint the frames with a liner brush.
With armor, I'll assemble anything that requires the camo color on the tank, including the road wheels. I don't glue the wheels in however, and I remove them and spray the rubber or weather the steel rims after the basecoats and washes are applied. This ensures consistent weathering and tonality on the model.
Pioneer tools, machine guns, or anything that's not painted in the camo colors will be added after painting is done. Tracks are generally added at the end, but before antennas and other fragile parts are added as the final step. Painting is typically an on-going process during the build, and I rarely follow instructions, at least as far the order of construction is concerned.
Ships are an entirely different story. I'll assemble and paint the lower hull first, complete with weathering and decals, then I'll build, paint, and detail each deck level, painting and detailing as I go. The final steps for ships are the photoetched rails along the main deck, and the rigging.
That's how I do it...
Jeff