Go to this website and download a booklet for stabilizer.
http://www.rnkdistributing.com/pdf-f...Stabilizer.pdf
It's great. For T-Shirts you use a mesh tear away. It is very soft against the skin you can also use a water soluable on the top to keep the threads stable. You also don't want designs with a high density count if possible. I take mine into my 5D Pro software and remove any unnessasary stitches to lower the density and add trim commands for the jump stitches. If you go to emblibrary.com you can check out there projects and also they have tutorials on how to emboridery on everything from t-shirts to balsa wood. When ever I go to any sites I check these things out to see what they say. Also, do a search on Floriani and John Deer classes to see when they might come to your area. Both are low cost and you can learn alot and get some great deals. Good luck.