Apart from waxing the other major causes of ingrown hairs is - wet shaving with a razor blade or safety razor - and also using an epilator.
Waxing and using an epilator work by pulling out hairs theoretically at the root. However method of yanking hairs from their follicles, often break off hairs just under skin level - the epidermis - leaving the jagged broken tip of the hair shaft to catch on the underside of the skin. The hair shaft will continue to grow but as the broken snapped off tip catches on the underside of the skin, As It has no place to go hair will grow sideways and sometimes downwards, causing infected red bumps, and the hallmark discoloration.
There tried and tested method of safe hair removal is using an electric personal shaver. Beauty writers and editors need to differentiate between an electric personal shaver with blades that do not touch the skin, and the safety razor or straight edge razor which both scrape away the protective outer of skin - the epidermis. These razors remove unwanted hairs as well as this layer of skin and also its precious natural skin oils, that later on you pay big money to replace with costly artificial oils, moisturizers and bump fighters to combat dry irritated and reddened skin.
There are many good personal electric shavers to choose from, which are quite different from the male face and beard shaver. They will not cause shaver rash red bumps or ingrown hairs (pseudofolliclitis barbae) or damage the skin which may cause the infection called molluscum contagiosum.
Doing an Internet search use "personal shaver" as a search term or something similar, to see the various offers. Check also that the foil holes are graduated in size to accommodate the different hair types and textures. Don't buy one where all the foil holes are the same size. You should not need to pay more than $50.00.