As I mentioned in another thread, I think the best defense is a good offense that is unlikely to be turned against you: massive lighting. Especially helmet mounted. If they can't see you, they can't hit you. And if you can see them, then the odds are pretty good.

If you're concerned about rocking the tactical lighting all the time, you could kick it up just in the more sketchy areas. But I'd have to think that, say, 1000 lumens directed wherever your head is pointed has got to be a pretty good deterrent to even approaching you, at least from the front. And anything that makes you more visible is going to make them more visible too.