Have a balanced attack. Say for example don't rely solely on just one card or a particular combo. Your cards must survive on their own so that you won't be hammered while waiting for your more important cards.
Having just one way of winning makes you more predictable and vulnerable to counter attacks by your opponent once he / she learns your combo.
You could also just use your favorite cards and that way you can always be pleased by the result of the performance of your deck.