Very bright colors. Because of my headache disorder, neon or near neon colors tend to bring up a nasty migraine, so I have to steer clear of those. I actually can't use any of the MSQC rulers or templates because the migraines I get from them are exceptional. That said, as far as designers are concerned, I stay as far away from Tula Pink as I can, which seriously depresses me because she has fabulous fabric lines, they're positively gorgeous, but there's no way I can work with her fabrics.
I'm not picky about where I get my fabric, if it's something that I like, naturally I'll comparison shop and try to find the best price for it. But if I'm lucky enough to go to a thrift store or garage sale and they have fabric and it's something that I like, I pick it up. The way I see it, our hobby is an expensive one to have, so any cost cutting measures I can take, I'll take them.