It also helps to keep track of which decks work, and try them again with minor variations if you get a good spin.
I find the area frustrating. If I make an original deck, I go 0-4 and drop out of the T500. If I make a "standard winning deck (tm)", then I can make the top 100 and earn a couple hundred electrum.
It's much better for me to submit monodarkness, fire rush, or an oraclebow, than make a really original deck.