Hi Richard,
I have seen a lot of stores with one theme, and a lot with multiple themes. I think either one can be successful, they both have their own pros and cons.
If you have one theme, it is easier to build your brand image and focus your marketing efforts on a specific target market.
If you have a lot of themes, you will have a better selection, and designs that appeal to many different people.
One thing to consider is that if you decide to do multiple themes, make sure your designs aren't in contrast to each other. For example if you had some politically-themed shirts, you wouldn't want a "Pro-something" shirt next to an "Anti-something" shirt.
I have seen a lot of stores with one theme, and a lot with multiple themes. I think either one can be successful, they both have their own pros and cons.
If you have one theme, it is easier to build your brand image and focus your marketing efforts on a specific target market.
If you have a lot of themes, you will have a better selection, and designs that appeal to many different people.
One thing to consider is that if you decide to do multiple themes, make sure your designs aren't in contrast to each other. For example if you had some politically-themed shirts, you wouldn't want a "Pro-something" shirt next to an "Anti-something" shirt.