I'd say start with monk since it's normally a good an easy choice. Just don't think that's carved in stone, there are some other great secondary professions that you might want to try later on.
and that's how you end with necros and rangers with mending and orison of healing...for god sake stop the monk abuse...
imo rather mesmer, take advantage of mesmer hexes who combine very good with necro.and necro tbh dun need explicit self healing, if he know what he do...
I based my choice on the fact this user is prob new to the game. Of course there is better choices but monk is a good one for a new player. Most people don't group during the early stages so a self heal is nice.