ClearHead by HeadBlade is my absolute favourite, it works wonders. Then there is things like Bump Patrol, which is good but for me, not as good as CH. Always do a cold rinse after you shave, or ice cube. Maybe go WTG on the back of the neck/head till it toughens up.
I'm not sure If this will work but try a 1 or 2 blade razor aswell, like a gillette disposable one. Less blade, less irritation. If you have a razor with 5 blades, then there is 4 more times a sharp blade is going on the skin, than if you was to use a one blade razor. but then again a 5 blade razor might give you a smoother shave as a one blade may not causing more irritation. Just a thought.