I find staying further out if you're on his six helps you stay alive better but the extra distance makes it a little harder to hit him.
If I'm not bothered about the cap and there's a group including 1 nova coming head to head with me, I stop dead at 3km out and fire on him with 4x AHEPTs only. A full load of them usually toasts a nova in one pass and since the closure speed is reduced by sitting still I find I have enough time to land enough shots on him to kill him. Just have to remember to strafe as they ingress and hit the boost key to hit full speed as the rest of the group passes, don't want to be left sitting still when all his mates turn on you.
If there's more than one Nova I'll usually fire a decent sized missile from about 8km away then turn and run from them until it hits or is shot down. If it takes out one of the Novas it's game on again using the above, if not, well I improvise
