Thanks for the compliment on my Red Riding Hood shirt! The best way to design an all over print shirt is to use the size limits provided by DBH, or whatever company you’re submitting to. It varies based on the type of shirt the company uses. When you design your shirt, keep in mind the shape of the shirt and don’t forget ladies shirts have a different cut than mens shirts. Once you have a rough sketch of your design done, place it on a blank t-shirt comp (also usually provided by the company you’re submitting too), to see if it fits the way you envisioned it to. It’s basically a bit of trial & error. Hope that helps & good luck!