Really? I haven't had a single ingrown hair since I went straight..straight razor that is.
But what I use to do before was to use a facial scrub after the shave..if you shave everyday remember too use a very mild scrub like the a dayly scrub. The more exfoliating scrubs shouldn't be used more than 2 times per week.

Now the scrub is not a guarantee against ingrowns but it does often work. Otherwise there are products made for this purpose..just check with your nearest skincare store.