Take the guesswork out of changing guitar strings
When winding a string around a tuning peg, strive for 3 complete rotations. This ensures the string is properly fastened to the guitar. The best way to hit this mark, every time a string is changed, is by using a trick I have picked up from playing over the years. The key is in knowing how much slack to leave in a string before it is brought to tension.
After you have initially threaded the string through the tuning peg, place your index and second finger perpendicular to the neck near the seventh fret. Your fingers should be shaped like an upside down V. Now, lift the loose string, no matter what the gauge, to the crook of your fingers with your thumb. By elevating the string to this height, it will leave the ideal amount of slack to be wound around the tuning peg.
By adopting this practice, you can take the guesswork out of changing strings.