Razor burn- only shave down there with fresh blades, and moisturize
Acne- wash down there with unscented
soap. Or an antibacterial
soap (DO NOT DOUCHE, in general, but particularly
with that
soap) my gyno recommend hibiclens, which you can get at CVS in the first aid section
Ingrown hairs- everyone's got a trick for these. Try not shaving, washing well, and even acne medication(Used sparingly)
Cysts- see a doctor, but that's really probably not it.