For me, razor bumps occurred when the razor didn't properly glide over my head. Usually this was due to a dull blade cartridge or using a shaving cream that didn't allow the razor to glide smoothly. If I didn’t use an aftershave balm that also contributed the problem. My head will be smooth, but at the end of the day or the next morning I'd have bumps, particularly on the corners of my head.
I use a headblade (sport or ATX depending on the day) and I try to make sure that I have a fresh cartridge on it. I also use HeadSlick. Personally, I find that it makes the razor glide over my head better than other creams. Plus, it’s mentholated. So I find that it cools my skin during the shave. It even leaves it feeling little cooled after the shave. Finally I top it off with an aftershave. Started using the Gillette aftershave and Nivea aftershave balm, but moved on to Taylor of Old Bond street.
This combination is what worked best for me and I can’t recall experiencing razor bumps in the past two or three years.
Hope this helps out