How to prevent ingrown hairs?

I am 17, I have a patchy beard+moustache combo. And I have heard that shaving against the grain can cause the hair follicles to be inverted and grow into the skin. And that double razors can collect hair and then embed them in the skin. And that using alcohol can also help to prevent them. My hair is too short to use clippers, help!! I don't absolutely need creams to shave do I?