The most common way to train is via High alching at level 55 Magic.
If you are rich, use teleport spells to level 55.RS 2007 Gold.
If not, you can cast curse on the zammy mage under varrock castle stairs.
Or you can use fire strike spell on fire giants (chance of rune item drops)
Note: If you curse of High Alch, you will not get any HP xp.
Other ways to train, if you are super rich, is to burst (lvl 70), or barrage (lvl 94) at Ape Atoll.
You also mage Metal Dragons (Iron or Steel) and hope for some Dragon Drops.
Magic level milestones.
Level 55 – Alching
Level 70 – Ice Burst
Level 82 – Ice Blitz
Level 85 – Tele block
Runescape 2007 Gold
Level 94 – Ice barrage/vengence
Level 99 – ownage