Mulligans vary depending on the Hero and the type of deck you are against. There are lots of tactics that can be used to defeat your opponent but it is generally quite safe to go with a tempo approach. I am aware that Tempo Mage has counters and struggles against specific decks but that doesn't mean it is GG from the get go. There is always hope.. (Like top decking a fireball for lethal *insert evil laugh*)

If you have no idea what you are playing against, my advice is to look for a good mana curve: a 1 drop, 2 drop and a removal spell. Your 1 drop is most likely going to be a Mana Wyrm; not only can you contest other minions but if you have a removal spell such as Flamecannon OR Frostbolt,  you can keep the Wyrm alive whilst buffing it. Pretty neat? 

Your 2 drop can either be Mad Scientist OR Sorcerer's Apprentice. Having a Mad Scientist generally allows you to pull your secrets from your deck, which help your maintain tempo. I generally prefer looking for a Mad Scientist since I find it the most influential card in the early game. In addition to helping you generate a board but once it dies, your opponent has to play a guessing game. This enables you to waste your opponent's cards or prevent them from playing large minions because they aren't too sure whether it is Mirror Entity or not. 

Sorcerer's Apprentice... It's pretty effective with the coin. Turn 2: Sorcerer's Apprentice, Coin, 2 Mana Removal Spell.  You must be cautious when you use your coin early because if you have nothing to follow up the following turn apart from Hero Power, it won't be beneficial in later turns. Sometimes, it may be better to just play a removal spell instead of using the coin. I usually look for a Sorcerer's Apprentice if I am against a Hunter because Animal Companion can easily be dealt with using a low costing spell while you maintain your board. 

Flamewakers are only good with spells. This means that playing it on turn 3 might not be the right thing to do. If you don't have a minion on your board, then you should always play Flamewaker unless you are feeling risky. Otherwise you are more likely to see a Flamewaker between Turn 5 to 7.

In the near future, the meta will change and I hope to write a more in-depth guide about how to mulligan against specific meta decks. Right now, I thought that keeping it quite general was the best idea as the Whispers of The Old Gods is being released soon and the deck will change. Once the new cards have all been released, a new Tempo Mage will exist (or so I hope).

See you in the next one!