1) Do not cheat. Cheating includes refreshing the prize page more than once per game*, sharing answers with members, trading the cards of your mastered set, and keeping cards you've traded away.
2) Follow the tradepost and log guidlines. They are on the About the TCG page.
3) Direct-linking is alright, as long as you take them down after the round is over. If it is something that I say you can keep for good (like an award or something), you'll have to save it to your own space after the round ends. I'm allowing this because I'm only using about 60 MB out of 120,000.
4) Use an easy, and original name. Try not to use Yuna or, something with a lot of numbers and random letters... or a full sentence.