Put one between yourself and your enemy. You'll notice that rockets still lock, even if you don't have a direct line of site on your enemy. So, you could be sitting behind a rock, have an enemy ship heading straight for you, and boom, you've a lock and they can't hit you. At this point, move from behind the asteroid and fire the rocket. Rarely will someone be able to dodge this kind of attack.
Proximity mines are also great, but only if used correctly.
Again, the best way to use these is when going head-on. Right before a collision might occur, drop it, and move out of the way. People fly into these things all the time. Another great use for these is mining commonly-used routes. Like the tunnels inside the asteroids.