one thing i dont think i see mentioned, which i just figured out in the last little while, is that when you are trying to get it even on the end where you are going to pop the hole, a few quick hard spins each way will help get the glass to flow all evenly at the end(centrifugal force), redistributing more uniformly in a short moment, and allow an even centered hole and lip. before i figure that out i had to usually keep tearing gobs off repeatedly to get a uniform end, unless it was a small tube.