[Lex]

^Basically that. Conceptualise as a series of deformed cylinders, plan ahead how many polygons you intend for each bit, and make provisions for when things blend in or out of the fuselage, like intakes or cockpits. If you have reference on how the cross section looked like, then it's a good idea to try matching those.

Having said that, a better thing to learn is how to use polygons to design complex surfaces in general. Vast number of CG tutorials and videos can help on that, and I think your question is best answered by learning such mindset rather than particular techniques. Aircraft model design is no different.