What interesting ways are there for a Mage to level up their skills? Besides blasting Shadowmere with Destruction of constantly casting Muffle over and over. I've never played a pure mage, the closest I got were Battlemages, but it's high time for something different

As for my magic style, I use all mostly equally, with a little more focus on Destruction, Alteration and Conjuration for a more offensive experience.

Not sure if I understand the question, but... what more interesting than earning those levels in combat?

Well, always have a follower with you. After combat, heal him. Cast soul traps in every enemy, Have money. Mages need several potions, staff, scrolls and so gems.

As I said, I practise every magic skill, just those three a little more. And there's more to combat training than combat, I figured people would have some interesting ways to get some practise in... After all, a Mage needs to practise safely before jumping in head first...

I'd like to meet the person who told you that

Here in Brazil we have a saying I will adapt it . "Mages are not like warriors, ogres who only swings its weapon. Mages are like graduated guys from the MIT" It reminded me this.

Unfortunately, "brutes who thoughtlessly swing cast their weapon" seem to be mages in Skyrim to a "T." Almost everything is combat magic this time around.

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Anyways, you can make a game of taunting mammoths or "experimenting" on your summons. Back in Oblivion I used to grind combat magic by summoning an imp then pelting it with Destruction magic. You could summon a relatively weak one, cast a flesh spell, and then brutalize it or cast Illusion spells on it since testing on people is a crime now. Then repeat. I'm not sure if you'll get any Conjuration experience from summoning, though, which kinda takes away some of the efficiency that Oblivion had with this sort of thing.

To a T.? Didn't get it. I experiment on travelling people, I feel like a psycopath.

Have your vamp earn their necromage perk suffering flames. A trial by fire that makes the vampire weaker by day and stronger by night.

The idiom or how they're like barbarians only with magic?

Read book, lean spell instantly, and only improve by casting in combat (save for a few select spells) doesn't feel very mage-like to me. Especially since you can't take the spell apart and put it together as something else. I realize it's all probably a game mechanic (since the majority of spells are combat-related, which is another problem) but it still feels very...brutish.

You're just scared of the novice spells, that's all

You shouldn't be.

Well, would be boring to see your mage reading a book for days. Is like the Dragonborn, In.Game mechanics limits his powers so the game wont be very easy.