Make sure you sterelize your razor. I used to get shaving rash a lot and it's not until I started soaking the razor in hot water with anti bacterial hand wish in it that I started getting less of a rash,also try find a shaving cream that prevents rash and that doesn't have alcohol in it,or fragrance because it can irritate the skin even more.Also try replace your razor at least every few weeks or so.Also after you have shaved,I find either a antiseptic cream,apple cider vinegar or dermaid cream helps as well.
i don't know why but it's really uncomfortable esp in the bikini area which is why I wax down there
exfoliate the skin you shave a lot so it stays soft and the hair can grow back with out being stifled by old skin. I usually use baby oil and Nivea lotion after I shave; works like a charm no itching for me