I've been a devotee of concealer, foundation, and contour from the very beginning.
Concealer and Foundation / Powder can do a great job of hiding facial irritation, especially from having to shave, bruises, etc. and just create the "natural, female skin" appearance. It takes practice and you have to find a formulation that's malleable -on- your skin while also matching your skin tone, but is so worth it. We call it "cover-up" where I'm from, and I daresay it's the single least-vain (or even apparent) step of make-up there is. If you put some practice into it now, you'll be able to hide discoloration, bruises, maybe even incisions if any of those are apparent.
The other big step is Contour. This is how you can minimize the appearance of swelling. Contour is about altering how the depth of the face is perceived. You can use if on the sides of the nose, for instance, to make it look narrower - and likely the same with a swollen jaw-line. Prominent forehead temples can be made to stand out less and look like they fold back into the hairline with a little contour, too.
These are makeup skills others stand no chance of noticing if you do them even moderately well, because it'll just look like a natural face. It's not mascara, eyeliner, lipstick, blush, eyeshadow, or that sort of thing. It's incredibly passive, but in my opinion, by far the most important aspect of makeup. If you're trying to stay stealth, not break any taboos, and really minimize any swelling or bruising, this is the way to go.