Hi Brad,
I took a look at your site and it is off to a good start. There are a few things I would like to point out.
You have a "products" link in the red bar, which takes me to a page with a link to your other product catagories which are ALSO listed on the red bar. Either get rid of the "products" link, or get rid of the "inspirational, creative, fun" links. It is redundant and confusing.
Each separate t-shirt design should have its own page with product info, pictures and description. For example, in your "Inspirational" section is set up like a product page. How are you planning to link to your cart this way? Will you have a huge drop-down list with the names of all the designs followed by the sizes for each of the 3 designs? Very, very confusing.
Instead, make the "Inspiration" page a catagory with pictures only, and link each picture to a new page just for that design. THEN put in your sizing info and price, along with your "Add to Cart" button, on those individual pages. Do this for all your designs.
I hope you are planning on taking more pictures of your products. Right now you have the same picture of a guy in a black shirt, with the different designs pasted on top. It is easy for customers to see that these are not pictures of the actual product, and even though that might be exactly how the shirts will look, it is still better if you have pictures of real people wearing real shirts.
As James also mentioned, you need to have enlarged pictures for your customers to see as well. This is extremely important.
Your "About Us" doesn't say much about you at all. The name of the "award-winning" design studio is not even listed. If you are going to use that as a reference, list the name and a link to the studio's website.
You should have a FAQ page with info about shipping and returns, a sizing chart, what kinds of payment you accept, and anything else you can think of. Look at other successful t-shirt sites for examples of good FAQ pages.
That's all I can think of for now. Please keep us updated as to your progress.
