For the wing skins, these just butt-join initially, and then you add a bandage to the inside of the upper forward section.

You have no access to the rear section after the wings are joined, in order to apply a bandage there. I therefore chose to glue some poly-ply strips to one wing half to create a "lip", which would aid in a better join. This can be seen between the rear spare and the TE in the pic below.