Cover the wing with yellow so that it is a finished covering job (I.E. shrunk and ready to fly)

Next I would draw (With a fine-tip felt marker) where the red is going to be (You can use the red pieces as templates).

Then I would just hand cut the openings with a #11 blade - Leave about 1/2" For the next layer to stick to.

If you look at the videos I did, I show the technique of sticking one covering onto another over open framework in Video #4 (Right after the "Benny Hill" music) where I lay the red tip over the white.