I build the wing or tail first depending on the manufacturer's suppgestions. You almost always need the wing to finish the fuselage so that's last. Once the wing and tail are built and the fuselage framed up I mount the tail and then the wing. This is important for alignment which you want right for a good flying model. I line the tail up with the fuse, and get the incidence where it should be. Then I epoxy it in place. Next comes the fin which can be set against the stab with a 90 degree triangle. Then I block the body up and work on the wing mounting. The wing needs to be level and the tips need to be equidistant from the stab tips. Once that's good, check the incidence. When all of the alignment's good I install any fairing blocks that might be required around the wing and stabilizer. Once all that's done I mount the engine and radio gear. I building my planes completely in the bones including all radio gear. That way I can move things around to get the balance perfect without added weight. When that's done I take the radio engine wheels, etc off and cover. Then everything goes back in and I check the balance again. It is important to plan all the electronic (radio), mechanical (engine/pushrods) and plumbing (fuel) before the plane is covered so if you need to change anything you can.