How to avoid razor burn and or red bumps when shaving the back of my neck?

I have my hair in a bun all the time, and the long brown hairs on the sides don't look right. I read how to shave my neck hair with a razor since I don't have a hair trimmer or an electric razor, and it warned me that I should be careful not to get razor burn or red bumps. Is there any kitchen ingredients I could use on my neck after I shave to avoid this?|||well do whatu do when u shave ur legs and such, use shaving cream.