I save the off-cut pieces of wood that the either the root rib came from, or the one that came from the fusalage, as this makes a perfect pattern of the curve of the foil your wanting to fare in.

Almost every time if you use that pattern to cut your covering it will come out perfect. The film(I use Monokote, but it all works) has enough give that you can easily get an overlap. If you take alot of care you can cut a hole out of it to clear your wing(using the very stock it came from for a template), cut it ever so slightly undersize and get excellent results, and you can cover your fusalage side in one piece. You only need maybe 3/16" overlap and then get a good seal on it and your set.

The patterns are a given in any kit, you just have to identify them and put them aside until you need them. I do hope this helps.