[Rata]

Wings still are my nemesis Don. If I have trouble with any build it's usually them.
A couple of things I've learned: preshape a bit curvature on the top surface (suitable size dowel or even a section of broom handle for larger models).
That way when you fold back the upper surface and gently massage in the leading edge with one hand while lining up the trailing edge with your other hand you've got a fighting chance of getting a more accurate and convincing looking cross section shape. Of course all the foregoing is done holding the wing down on a flat building board.
I don't try and glue the trailing edge in one hit. A bit at a time and running finger tip along the trailing edge while holding each corner of the leading edge down with my other hand to (hopefully) avoid warps.
I've also learned to NOT glue the wing-tips until the wings are attached to the fuselage- much easier to get that tip incidence right while looking edge-on with the fuselage as a visual reference. An exception is the top wing on a biplane which gets the tips glue before attaching to model.
I now have a pretty solid 90% or so success rate with producing warp-free wings and hope the foregoing helps.

GG