Staying away from full-on ATG passes has really helped for me, but it will likely take some experimenting to figure out what works for you. Try to only change one thing at a time and give it at least a week before changing anything else.
I switched to a double-edge safety razor, which has helped a huge amount. I can shave ATG now if I want to, with minimal chances of razor bumps, although I still get more irritation doing so. For me, the problem is folliculitis, not ingrowns.
I have very coarse hair, hence very large, open follicles following my shaves. I have to use alcohol-based aftershaves and occasional use of benzoyl peroxide and salicylic acid products to keep the bacteria from getting into my freshly shaven follicles.