Typically you should apply a darker color over a lighter one...if you apply yellow over the black, it will "bleed" through if you used black as your base. That being said, I'd cover the entire wing in yellow first, then cut your black stripes to the desired width and iron them down over the yellow. You probably should sand away that black over spray around the landing gear as well, so it doesn't show through the yellow covering.

You could cut individual stripes of yellow and black but it'll be much much harder to cover that way and get a smooth finish imo.