Here's a great Fender Article we found on Guitar Tuning. Many guitars can go out of tune sooner then you think, so hopefully today's lesson can help you
ovecome this common problem.
Tech Talk is going to keep it short and sweet this time by reminding you of a simple but highly effective principle to keep in mind when tuning your guitar or bass.
It is merely this: When tuning your strings, tune them up to pitch rather than down to pitch. Tuning up rather than down results in more stable intonation.
It’s simple but important, especially if you’re dealing with new strings that you’ve just installed. You want to increase string tension up to the desired pitch rather than decrease string tension down to it, because the strings “grab” the tuning posts on the headstock much better when they’re being tightened rather than when they’re being loosened.
For example, when tuning the high E string of your guitar, you want to make sure you’re “coming at” the correct E pitch from below; say, from a half-step or two beneath it (i.e., D and D#). This way, you’re tightening the string and thus increasing its grip on the tuning post, making it less likely to loosen and go flat a bit when it’s subsequently picked, plucked or strummed.
If you tune down to the high E by coming at it from a half-step or two above (i.e., F and F#), you’re physically loosening the string and thus slightly relaxing its grip on the tuning post, increasing the likelihood that the pitch might slip down a bit further when the string is subsequently picked, plucked or strummed. And if you go flat even a little, someone is bound to notice.
When tuning, the source of the reference pitch doesn’t matter—be it an electronic tuner, online tuner, another guitar, a piano, pitch pipe, telephone or whatever. Tune down to a half-step or two below the indicated reference pitch, and then slowly tighten the string until you reach the correct pitch. Then you’re good to go.