RE: SIG 1/5 scale J3-Cub
What kind of landing gear are you using. the kit supplied, or a scale aftermarket? The scale gear really adds to the looks, and improves ground handling and landings, IMO it's worth the money if you're putting a lot of time in the build. Robarts and Wm. Wallace both make a nice set.
What covering? Koverall is beautiful, and if you don't want to put so much work into finishing, Solartex is great, too.
Since the wing struts are functional, I pinned them where the metal attachments fit into the slots, as well as following the instructions. Pin them before you wrap the ends with fiberglass and epoxy.