So, on optomizing your deck: Keep it simple. Go for one strategy, stick with it, and tweak the numbers. Look at every card in your deck, and ask yourself 'Why is that there? Does it fit my strategy? Is there a better card that I could put in that slot?'
I highly recommend reading
SG's 9 tips for better deckbuilding.
Another useful tip is in looking at your
Quanta Index with UTAlan's
QI calculator.Your deck seems to be alright quanta-wise, though it could be better. In terms of strategy, it is solid in composition, though lacking in real strategy and design. Your deck balances its quanta and card usage well, but spams creatures with little regard to speed or control. What victory condition do you plan on having for this deck? Beating at your opponent with creatures is only a good idea if you can do it faster than your opponent.
On your choice of opponent:
By Arena level 4... you mean platinum league? I would stay away from that for now. It was designed to give players with fully upped card pools a difficult challenge. Attempting it with a completely unupped deck, no matter how good it is, is not advisable.