I have had a few people ask about the design programs used by South of Memphis.
I use Adobe Creative Suite, mostly Adobe Illustrator to create my designs in because vector art is scalable to any size and generally has a smaller file size to work with.
Smaller file size when working with graphics is always a plus because it doesn't take as long for your computer to process the work. I do use Photoshop too but I prefer Illustrator for the clarity, scalability and the smaller file size. Also the vendor I prefer to work with will take native Illustrator files right into their mock up generator which just makes life easier. No wasted time having to switch file types etc. It is especially helpful when dealing with transparency issues too.
I've always been partial to vector based artwork which is what most of my tee designs are done in and have used Illustrator or for several years and at one job Freehand for technical drawings. To be honest those really should have been done in CADD but the owner wouldn't spend the money on it.
After working in print design over the last 20 years of my career, I am particularly well versed using In Design as well which is great for publications like brochures, flyers and business cards and other printable documents. If you need more than just t-shirts or could use a full matching branding design I can do that for you. Just ask!
My advice to anyone just getting started using the Adobe Creative Suite is to just start experimenting, download or watch tutorials on various uses and tools and if you plan to go to school for graphic design, choose a trade school rather than a full on 4 year program. You can always finish up your BA after you get your AAS in Graphic Design.
The reason I advise budding designers to this, is because I lived it. You get more hands on training on computers and in the software you'll use daily by going to a technical type college for 2 years and then transfer to a 4 year institution to get that degree everyone expects or you can target it more by getting your degree in marketing for example. A Graphic Designer with a Marketing Degree? Creative departments LOVE that because you know the ins and outs of marketing and how being too artsy can sometimes flop when selling to regular Joes and Janes of the world.