No matter what technique you use to change strings an instrument, one brief word of advice based upon experience:

Never trim your strings until after you've tuned the instrument up to pitch. If you should mix up, say, the A & D strings and you've already cut the excess off, you're screwed. One of the trimmed strings will be too short to reach the proper tuning machine.

I did it once, about 35 years ago, and I haven't trimmed a string since then until after I've tuned it to proper pitch.