Right, definitely don't let yourself get distracted by the minor enemies. They come back faster than you can kill them.
If you're not already doing it, lock on to the part you're targeting, so you can focus more on staying alive and less on aiming.
A spicy roll (after the vulnerable bits are exposed) will also help tremendously, just keep in mind that there is more than one of these monsters and they're not even toughest enemies around.