First thing... have you created or gotten yourself a website that would would allow you to have an online products page? If not go to http://office.microsoft.com Microsoft is offering their new MS Office Live Basics website for Small Business owners and aspiring ones. I have mine set up through them. You get a free registered domain name, (25) business email accounts, ad management through google search. It's great! Now back to your questions...

Are you in a college town?

Why is your focus on targeting mothers?

How will your t-shirts appeal to mothers & college students?

Are you using an interactive design site like www.uberprints.com to help in creating proofs to market to your buyers.