first you need to get a P.O. box address for your business. then you need to find a reputable website designer. Don't go cheap on this. The difference between selling and not is that little extra flare. You need to make sure that you attach your page to everything you can Google, Yahoo, hotmail, babys'r'us, anything that will let you attach your product to them. Also try getting some of the children's stores to let you put posters up with some of your product. Make sure that you have the rights to sell the T-shirts that you are putting your design on. the original Manufacturer of those shirts can give you a major headache if you don't. You will need a business license and name (that is not already taken, your local city offices can tell you what's available). You will also need a sales license. Business and sales license are two different things. You need a catchy slogan something that will draw attention (advice: don't use anything cheesy people stopped responding to cheesy in the early 60s).
Other major things to concider are, what kind of demand is there for your product? who are you really marketing to? Is this the right time to start this venture? Are you really willing to follow through with this or is this just a fleeting whim? Do you have the financial overhead? Do you have an escape plan if this doesn't work out? Will this venture provide the stability you need? Do you have the ability to expand if you need to? Do you have the drive to expand if you need to? Do you have the time to do this? Do you have the means of keeping good legal documentation? Do you have a good legal/financial advisor?
Starting a business isn't anywhere near as simple as one would think it is...
