Regarding creating a design to put on a product such as t-shirts
that you use some online maker for...
There's a handy little feature on http://www.Zazzle.com
Mouse over the tab at the top as if you are planning to shop... A menu area will pop up. It gives you a list of hottest products
, mugs, t-shirts, etc.
Yeah, it's a little vague, but if you have a preference for one of these hot products, you can design your store around that for maximum effectiveness. Who knew doormats would be a "hot" item?! And the water bottles... people spend how much on what?! Work those royalties permies! Those seeds and seedlings aren't going to buy themselves!
Also, here's some free training
for handmade businesses (which you can learn from for any business --like launch 10 piece product lines).
Much love to all the permies.