Oh my, I think I have found my new favorite thing…onesies! A year or so ago I bought a heat press. A friend asked me to make a onesie for her and the first one that I did I scorched the shoulder seams. I have since learned that you need to elevate the area that you are pressing so that it is higher than the rest of the onesie. You can do this by placing a folded wash cloth inside the onesie or by purchasing a Teflon pillow to slide inside the shirt.
red capped blade
When making anything with Heat Transfer vinyl you need to make your design and then mirror the image so that when place on the shirt it reads correctly. Then place the vinyl on the mat so that you are cutting the vinyl and not the carrier sheet. And lastly, you weed the vinyl. Once you have it weeded you line it up where you want it on your shirt and then press. There is a lot of online help for determining proper placement.