To use bind and Bounty to train your magic up!
As most of your opponents are fierce when using ranged attacks, it is not effective to train Magic in Bounty Hunter.
If you want to try this way, it is suggest you buy a runescape account to join a member of runescape. Or you can read Magic training in Runescape on Farmer100 blog for you to train Runescap.
You can go to a bank to sell the drops that from attack and strength training. Store all the items except for the amulet and withdraw your staff of air, chaos runes and mind runes to start training Magic in Bounty Hunter.