I've read several fancy ways to avoid the other great bugaboo of vac kits, sanding off too much at thin spots when dressing down the mating surfaces, but I just keep checking progress and shifting my grip around on the part so I'm not always bearing down on the same place.
(Another thing: if you want detectable progress, use 100 grit or 120, but nothing finer.)

A little here... ...and a little there...

...and a lot more on those trailing edges. I avoid excessive wear and tear on the thin leading edge of the wing by keeping the smooth center of a coarse rasp on it while working the trailing edge in short strokes:

Working along the edge of the sandpaper (stuck to my countertop scrap here with double-stick tape), I avoid sanding on the leading edge until the trailing edge is nearly done. All the flat parts are sanded with duct tape "handles" like this. They're messy but strong and I pull off the clinging adhesive with masking tape when the sanding is finished. Again, keep shifting your pressure points around and checking progress: