I too used to do t-shirt painting LOL!
We sell a lot of transfers (I'm lucky and have a press) and one thing that really helps, it to not press it as you print it, in a square. Hubby cuts sort of close to the design, and sort of squiggly, so as to not have any sharp corners. We also don't put a hugh design on, especially if you will be wearing it in the hot months, since it makes the shirt hotter. Good luck with your endevor. I really so suggest the cold peel..I think it's better if you don't have a press. One more thing.. the transfers work better on freshly washed shirts, with no dryer sheet or any type of softener used before applying. And we suggest washing them with the item inside out. We do say no dryer, but no one listens, including myself.