Couple of suggestions: when putting in a new tube, put some baby powder on the tube before installing. This will allow it to move a bit in the tire, so it isn't folding over on itself. Also, take the tire off the rim and run a cotton ball or used drier sheet around the inside of the tire. They will snag on anything inside the tire (much better than finding a glass shard with your finger!). I don't tighten the valve stem nut (many don't even use them).