Make sure theres a tip at the end, and also make sure that when the last bit of paper is being rolled it is not parallel with the edge. If you do this you will know what I mean (if you dont understand that wording) because it is hard to get it taped when it is like this.
Tape the end
Lick the end and make the paper stick to itself
Cut of the excess "tail" at the end
Also if you have holepunched paper, and there are holes, make sure that the tip does NOT have any holes and no holes are showing. This is for Aerodynamics