I've done a few things to help avoid boilovers. Generally, the foam will increase and peak as you add hops at the 60 minute mark. This is really the most imminent threat of a boilover at this point. I always feather the flame down almost to idle and stir , trying to knock down the foam. I've also fanned it and sprayed a water mister at it, with varying success. Once it breaks, you can gently turn the flame back up a little and usually just go through the rest of it without too much hassle.
A general rule is that if you're adding hops, they'll cause a bit of foam to be generated, even later in the boil. A friend and I were brewing an extract batch at his house, and even though we were 5 minutes away from the end of the boil, I haphazardly threw in the 1oz hop addition without adjusting the burner. A major boilover occurred and he lost almost 1/2G of wort.
My general rule is to always feather the flame and keep it high enough to just barely maintain a good boil, and always turn it down when adding things until you can bring it back under control.