So I'm trying out my first mage character and guess what? Rushing in and taking enemies head on doesn't seem to work. Can someone explain to me the best way to use a mage?

Try to spend magicka in advance of the fight and recover it back while still gaining most of the benefits. Like, you can cast a rune on the ground, wait for your magicka to recover, then cast oakflesh, wait for your magicka to recover, then summon a creature and start the battle.

You....you want to be a mage?...WHY?

It's ALL about the one hander + shield

Teach me how to dougie.

Preparation is the key to success. First keep a combat spell in your right hand and use your left hand to switch between defensive and summoning spells. You have added all your spells to your favorite list right? Then assign numbers to all your favorite spells so you can quick change them in battle.

Summoning minions seems to be the way to go, and supporting those minions.