I would also add that you should have fun doing it. don't look at it as work or as a way to make a quick buck. everyone recycles the same ideas over and over again, the key is to do your own thing rather than doing what the other guy is doing. come up with a theme or just go with stuff you'd personally wear. if there's one thing i've noticed with t-shirts (brand or no brand) is that there's a lot of crap out there and people will buy it no matter what, because we're all pesky consumers.