I play the guitar:	Change your strings every:
2 hours every day	2 to 3 weeks
30 minutes to 1 hour a day	1 month to 6 weeks
30 minutes to 1 hour 3 to 5 times a week	6 weeks to 2 months
almost never or never	2 to 3 months

    Actually, you should change your strings any time that the unwound ones don't feel smooth when you run your finger along them, or if your guitar has gotten very hard to tune. Dirty strings lose their ability to resonate the harmonics of each note, and these are the source of the brightness you hear with new strings. By the way, if you wipe your strings down with a lint-free cloth every time you stop playing them, you'll extend their life by at least a factor of two. Make sure the cloth is lint-free!! If it isn't, you'll shorten the strings' life by leaving bit of cloth between the windings.

    One thing that helps in changing strings more often is to have a good supply of new strings in stock. Buying strings in quantity is also the way to get the best prices. Personally, I usually buy mine on Ebay, because there's always someone selling strings at great discounts. I just bought 12 sets of Ernie Ball strings and paid $2 and change per set. D'Addarios, which I use on my acoustics, are more expensive - for 10 sets, I paid about $3.75/set.

Pickup Height
    This is a very individual setting, and is unique to each guitar, brand of pickups, and style of the guitarist. It's a VERY good idea to do this adjustment with new strings, because the differences in tone you'll be listening for, especially when you're nearing the perfect height, can get very subtle. First, finger each string, one at a time, at the highest fret, and measure the distance from the string to the top screw of the pickup. It should be between 3/16" to 1/4". Adjust the height of the pickups using the small screws on the side of the pickup - NOT by the screws that are part of the pickup and almost touch the string!!

    Next, turn on your amp, and adjust the tone and volume to the approximate points where you usually play. Adjust one pickup at a time. I usually start with the one closest to the neck. Raise it slightly - say, by 1/4 to 1/2 turn of the adjusting screws - and play the guitar for awhile. You'll probably notice that both the volume and tone will have changed. Keep making adjustments like this until you hear a muddy, crunchy, overdriven sound (sometimes called the "wolf tone"); this indicates that you're too high. Back off on the adjustment screws by the same amount you've been raising them until you find the ideal height - the "sweet spot". Move to the next pickup(s) until you've found the sweet spots for every one. Your axe should sound louder, more full, and more responsive than it ever has.

Intonation
    The word "intonation" refers to the accuracy of the frets' placement so that, for instance, the 12th fret is exactly one octave up from the free, open string. The easiest way to check this is to hit the harmonic at the 12th fret and see if it's exactly the same pitch as the string when fretted at the 12th fret. To strike the harmonic, barely touch the string directly over the 12th fret and pick the string firmly. You should hear a very clean note one octave above the open string. If you look carefully, you can see the string vibrating between the bottom bridge and the 12th fret, and also between the 12th fret and the nut (below the first fret). Right at the 12th fret, though, you'll see no vibration at all; it's a "node" in the vibrating string. It's analogous to turning a jump rope slowly and then turning it much faster; I'm sure you remember that, when turned much faster, the rope divides into two halves with each half turning but with almost no motion at the rope's halfway point.

    To summarize, the intonation at the 12th fret is the true octave, and the note resulting from fretting the string at the same fret should be identical. If the fretted note is sharp, the string is too short; use one of the screws in the bridge to pull the bridge for that string farther back to lengthen the string. Similarly, if the fretted note is flat, the string is too long and must be shortened.  In the photo to the left, the intonation is being adjusted by using the six long screws, each of which threads through a steel anchor through which each string pases and is held.

Bridge Adjustment
    The bridge can be adjusted in two dimensions: it can make the string longer/shorter and higher/lower. The string length will have been done in the preceding section to adjust its intonation. How high the string is determines its distance from the frets, or the action of the guitar. Most, but definitely not all, guitarists like the action to be as low as possible without incurring any string buzzing.

    The best way to start is to look for any low spots, i.e., individual notes that buzz, usually because the fret directly in front of each note is too high. To do this, you need to play every note on the guitar. The easiest method is to place the little finger of your fretting hand on the fourth fret of the high "E" string, pick that note, then move down, one finger per fret, ending with your index finger on the first fret. (Incidentally, this is an excellent exercise in using your little finger and in alternate picking.) Then, repeat the exercise on the "B" string, then the "G", the "D", etc. When you're done with the first four frets, start over on the high "E" string with your little finger on the 8th fret (a "C"), moving down to the fifth fret ("A") with your index finger.

    The photo to the left shows a bride with the screws for adjusting both intonation and string height.  The six horizontal screws under each string adjust its length, and the large thumb screws at either end of the bridge adjust its height.  Unfortunately, with this model, adjustment of each individual string's height is not possible.  However, it is almost never found that adjacent strings are at widely differing heights.

    Keep repeating the same exercise until you've played all six strings in all five left hand positions, and you'll have played every note there is, except for the top three frets for each string. We usually don't worry about them, since we seldom play the notes up there, and when we do, we don't exert enough force to cause any fret damage.

    If you're like many guitarists (including me!), you'll find yourself turning this into a speed drill! That's fine, but make sure you do at least one run slowly enough to really listen to every note for buzzing - after all, that was the idea in the first place... ;-)

Truss Rod Adjustment

    The truss rod is a steel, reinforced rod that runs the length of the neck, and is anchored above the nut and at the bottom of the neck. Its purpose is to prevent the neck from warping or twisting; since the neck is wood, warping/twisting would be amazingly easy without the truss rod.  The photo to the left shows a guitar neck being assembled; it is ready to have the truss rod (on the left) inserted into the groove cut for it in the neck.  Shortly, we will get a much closer view of the truss rod; it can be seen that the rod is never just a simple round rod, but has variously shaped steel holders for it, whose job it is to suppress any tendency to warp or bend.  Remember - six steel strings, pulled tight enough to reach the six notes that they are tuned to, exert a tremendous amount of tension on the wood neck, such that, without the reinforcement of the truss rod, the neck would bend hopelessly out of shape in a short time.

    So, what is the ideal shape for the neck, to support the power of the six strings, while enabling them to be fretted at every position without buzzing or making unwanted noises of any kind?  Hundreds of years of experimentation by thousands of luthiers (guitar-builders) have shown that the ideal shape is slightly warped to a concave shape.  The truss rod is installed such that increased tension on the rod causes the neck to be less concave, i.e., the neck becomes straighter.  Loosening the bolt on the end of the rod allows the string tension to pull the top of the neck "up", deepening the concavity.  The diagram to the right shows this well.  Too much loosening, as just mentioned, causes increased curvature of the neck, raising the strings from the neck and making the action worse.  Over-reacting and over-tightening the rod would cause it to flex the other way (2nd diagram), laying the string along the frets so the guitar is unplayable.  Backing off on the tension would straighten the neck, where the action is still too low; but a little additional loosening would allow a small curvature, with the strings raised just a little from the frets - this is what we want!

    This short page covers standard preventive maintenance in only a superficial way, although the truss rod typically doesn't need adjustment more than once per year at the most, unless you take the guitar to a much different climate.  Changing the atmospheric pressure or especially the humidity can drastically alter the guitar's equilibrium.  If you'll be in new surroundings for only a few days, I wouldn't adjust the guitar to them, but if you'll be spending several weeks or more, it would be worth it.  I recommend waiting until you've been in the new area for at least a week, to allow the guitar to do most of the complaining it's going to do.  That way, you should only have to adjust anything once.  I'll address how to fix problems that arise in a future update.