Adding the disclaimer that I do not consider myself to be an expert, here are my two cents.
Currently your deck contains a lot of single cards, which adds more randomness than necessary. It might be a good idea to focus your deck on a certain theme and adjust your card selection accordingly, taking more double cards than single ones.
As it is now, your deck is a mixture of multiple things. 4 spell power minions, a couple of spells and some high end minions. You might want to focus specifically on aggro or spellpower. A Dalaran Mage, for example, is a pretty weak creature, but if you can combo it with Backstab (which is a staple card in my deck), it becomes a lot more interesting. There are better choices in terms of spellpower minions, though (another Azure Drake, for example).
That being said, if you could tell me what exactly you want your deck's focus to be, I could give better advice! This also applies to your mana curve, although I do think you could do with some more cheap minions in any case.
On to your current card selection, these are the ones I would definitely change:
- Preparation: Most Rogue spell cards are not that expensive, and unless you make use of minions that have a direct benefit of playing lots of cards (Van Cleef, Questing Adventurer), I would replace this one.
- Ironbeak Owl: Not too big of a fan of this one. Its silence effect is nice, but I rather take a Spellbreaker over this one. Again, this one becomes more interesting in a deck with Van Cleef and QA, but currently, I would replace it.
- Fen Creeper: High cost taunt minion, which does not change much at the stage at which it can be played. Taz Dingo > Fen Creeper any day, and furthermore it might be wise to instead of this one, put in a Defender of Argus or Sunfury Protector. Both more versatile and useful cards, if you ask me.
In replacing these cards, I would consider taking another SI:7, Backstab (!) or perhaps another Defias.
More changes could be made but again, this depends highly on what exactly you want your deck to be focussed on, so please do let us know!
Edited by JorZ on 12/20/2013 4:05 AM PST