I would also recommend you look both at how real healing works and at how other authors have addressed it. In Richard Jordan's Wheel of Time series, the Aes Sedai heal - you don't even have to go beyond book 1 to see how he handles it. In Orson Scott Card's Alvin Maker series, Alvin learns how to heal - this is particularly interesting, IMO, and worth a read - again, you don't have to go beyond the first book, though one of the later books might add to what you get in the first book (the one where his brother visits Napoleon and the one where Arthur is learning about healing). Those two jump to mind immediately, but I'm sure there are several others you could study to see how different authors have handled it.
I think it's key to understand how your magic works - does it use natural laws and speed them up, does it bypass natural laws, or overpower said natural laws, make use of natural laws that don't normally come into play, or...?
FWIW,
Liz