But I am watching...
In the past I have done batches of shirts and I end up with lots of leftovers in odd sizes. In fact, I have quite a few right now. Everyone says, "Do something other than black!" and then everyone wants to know if I have anything in black...
That gets expensive. I have also done the prepay thing where everyone pays for what they want by a certain date and then I have them made. That works fairly well. I have done black, tan, blue, and red shirts.
Over the years my biggest problem has been finding someone that can do good original artwork, versus just using clip art type stuff, AND that is actually reliable at getting me the artwork when they say they will, even when I offer to pay for it. I guess the artsy types are just kind of flaky
By original art, I mean I like stuff that is hand drawn and not just something cut and pasted together from a library of images. I've rarely seen any of the latter that I have liked.
Artwork with multiple colors is expensive because you are charged PER color. However, 2-3 colors is usually not too bad. You just have to keep in mind that the design will look different depending on what color the shirt is. What looks good on one color may not look so good on another.
I tried doing the CafePress.com deal for a while. Few people used it and their cut is so high that I make very little unless I charge a LOT for something like a T-shirt.
I prefer the silk screen shirts versus the iron on type. They tend to last longer and breath better at the point where the artwork is located.