Yup, listen to Swordwiz, go train with a medicine manual. The higher your healing stat, the better goodies you make (such as Hei Yu Duan Xu Gao).
There's another technique which I used. Run and Gun.
1) Hit them as hard as possible, as many as possible.
2) Repeat 1 till you know you can;t stand another round of attacks.
3) Run. As far as possible and heal. (if you are at the final battle for example, run up and down the corridor, from the very top to the very bottom. They will follow you)
4) Repeat 3 till about fully healed.
5) Go back to 1 and so it all over again.
Of course you have to be smart with this. Always know how much life you have and how many of them can hit you and how much damage they will make. Not all of them will be able to keep up with you when you run. Some of them can't hit that far. Slowly wittle down their numbers at first with wide attacks and then use high damage single target skills to pick them off one by one. If they are very far away, you can still use wide area attack to hit even further.