Well, usually, Water is a more focussed element that is much harder to play in the beginning. Fire and Darkness, as has been said many times in this forum, are your best bets as a newbie. If you don't have the money to switch, or don't want to start over, here are some helpful tips.
Keep the deck thirty cards and of a single element.
Try to balance Pillars to cost. If you're using a lot of dragons, bring more pillars. If you're using a lot of lower cost creatures, then you probably won't need to many.
Use Freezes and Ice Bolts on major threats (Otyugh, Mind Flayer, Fallen Druid, Dragons), not just any creature.
The Ice Shield is your best friend, but it can be stolen easily, and then used against you (though the AI3 doesn't do this often).
Lok around this forum and see if you can find some other helpful tips, or ask in the chatroom. There are usually always players willing to help and give advice. If you want, post your deck here, either as a picture or a list, and we'll see what we can do to make it better. =D