Magery Skill

You can use scrolls on level higher than your ability. You will easily and quickly gain skill just by normal use.
There are 2 other skills required to make your Mage an effective combatant they are
Evaluate Intelligence and Meditation.

Once you reach level 6 buy some gate scrolls and go do a ton of noble escorts the escorts will more than pay for the scrolls, you'll gain good reputation and all the while gaining skill in meditation and magery.