The best thing to do is prevention. Slow the stitch down and stay with the machine and watch it. I have ruined large and small items. You can roll the edges, use clothes pins or pins. I don't like using hard foreign items such as pins because what if your machine starts sewing it up. I spent too much on my machine to ruin it for a $10.00 piece of clothing. You can make a nest with the garment not being embroidered. The other thing to do is open up the side seams so your garment is more flat and not likely to get caught. Recently I ruined a sweatshirt because I walked away from the machine. I was emboidering words across the back and the weight of the sweatshirt pulled enough to make the VERY LAST letter messed up. I get frustrated and am still learning new things. I've been embroidering for about 5 years now.