I've been designing shirts for a few years now, so I've always been interested in printing my own designs. I took a tour of the Austin-Round Rock Techshop a while back and of course the screenprinters caught my eye. After a few weeks they were offering a class so I couldn't pass it up. It was a great experience, the class was very small (me, another woman, and the instructor) so we had plenty of time to ask questions and get to know the machinery. I found out that screenprinting is a simple but rewarding process! All of the required materials are available at Techshop except for the shirts and the ink, which is a pretty sweet package.

Step 1: Design and Vinyl Cutting

Even though I have some designs in mind, for the class we just stuck to some stock designs. We pulled up a few fonts from www.dafont.com and each of us got to choose an image that we liked. Because fonts can be scaled and easily converted into vectors, they are a good place to start if you want some simple images at no cost. Make sure to flip your image on the computer first, unless you want backwards designs!
After deciding on a design we cut it into vinyl using the handy vinyl cutter next to the computer workstation. Using the vinyl cutter requires a separate SBU at Techshop, but we were able to use it for the class. From there you remove the pieces of the design that you want to be inked onto the shirt. We attached the rest of the vinyl (which is essentially a big sticker) to the screen, and taped off the rest of the screen surrounding the design so no ink goes through.

Step 2: Actual Printing

After putting the design onto the screen, attach the screen to one of those blue arms, taking care to make sure your design is centered and straight. Spray some low strength adhesive to the table where you are going to place your t-shirt, and pull the shirt onto the table, again taking care to make sure it is centered and smoothed down.
For this class we mixed pink ink out of red and white Speedball Ink, which is a pretty cheap water based ink. After mixing your desired colour, use a palette knife to dispense a line of ink parallel to the top of your design on the side of the screen not facing the shirt. Use a squeegee to lightly pull the ink down over the design to prime it, then pull the arm of the printer down until it clicks into place. Now you're ready to print! Pull the squeegee towards you, pulling the ink across the design. Be sure to use firm, even pressure for a clean print.
Lift up the arm of the printer and your design should be printed. Water based ink will dry after a day or so, but to speed up the process we used a heater (shown in the picture, that black thing between the trash can and the amp) to cure the ink in about 30 seconds.

Step 3: Finishing Up

Now you have a screenprinted shirt! After printing wait 24 hours before washing or wearing it. I ended up printing 3 shirts that will see a lot of use. Go forth and change fashion!
I made it at Techshop. See http://www.techshop.ws for the closest shop to you.