Honestly if you're set on playing Mage, for just starting off and learning the game, I'd just throw in the core spells like Fireball, Frostbolt, Polymorph, etc. and a balanced minion curve. You can probably get through to at least 15ish without netdecking and while still learning the game which is what I'd recommend.
Past then, there aren't many viable Mage decks for more competitive laddering aside from maybe Freeze Mage and Tempo Mage, both of which are extremely pricey and require DLC. And even then they're not that great.
Warrior, Hunter and Warlock seem to be all the rage these days. You can construct Midrange Hunter, Zoolock, Face Hunter, and even the ridiculously ****y Patron Warrior for fairly cheaply and they're all top-tier decks right now. Face Hunter is the epitome of low skill floor, high skill cap as you can pretty much faceroll with it until you get placed against better players, which the deck is very difficult to play at that point, but still effective when played correctly. Zoolock is in the same boat. Patron Warrior is a very combo-heavy deck, harder to learn, but arguably a Top 3 deck in the meta right now.