Glue guns!
The biggest problem i have found with glue guns is stringing hot glue across the finished project when I glue the last spot. Most the time, sadly, this cant be prevented, but don't trow your project out the window and start over right away, sometimes it can be fixed with a little magic! When you are crafting with nonporous materials, such as glass, metal, and most craft wood, its easy to simply wait for the glue to harden, peel it away and start over. But for the more uncooperative materials, like felt, paper, cotton balls and most fabrics, fixing the mistake is a little more difficult in these cases, you can ether wait for it to dry and try to snip it off with sharp scissors or resoften soaked-in glue by pressing the hot tip of the glue gun against it. ( Make sure your glue gun is working properly though, because if its not that could just make your problem worse.)