Best way to shave bikini line?

I wait until my disgusting bikini line is long enough to shave so that it doesn't scrape my skin half to death, then i shave it after soaking it in warm water and coating it in some conditioner (unscented, not the flowery stuff that irritates sensitive skin). I shave carefully and don't go over it over and over, and I use store brand little razors but not old gross ones that have been used too many times. And my bikini line is still red bumped and has its own version of a five oclock shadow after a couple hours. What do I do? I can't keep suffering through the whole ten-days-of-prep before I get into a bathing suit. It's depressing.