why keeping your strings clean does much more than preserve their sound

This is more important than you might imagine. Why?

I'll give you an example: I knew a guy who bought a brand new Strat Plus. He played it for 18 months and asked me to have a look at it, set it up. I couldn't believe my eyes when I looked at the frets. They were so worn, I thought the guitar must be five years old and well played. No, it was 18 months old, and this guy just played it four evenings a week in his living room! Then it hit me. I asked him: "When did you last change your strings?" He replied... "These are the ones that came on the guitar."

I ran my finger along the underside of the top string; it was very rough, covered in grime. I realised and explained to this poor guy, that this dirt, stuck to the underside of his strings, had worn his frets as much in 18 months as I would have expected in 5 years. He was upset, naturally.

Once your strings become grunged up and corroded underneath, they act like sandpaper or a file on your frets. So its very important to change your strings regularly, or at least make sure they are clean and smooth underneath.

I recommend that if you play regularly, you should change them once a month or more, and you should really clean them every time you put your guitar away for the day. A soft cloth is all you need. What you do is to put the cloth under each string in turn, and run it up the length of the string several times, until no more black stuff comes off.

If you play professionally, you probably change your strings before very gig or recording session. The reason for this is that, a string (even if kept clean) looses its best tone after a few days of playing. Some people insist that their strings loose their best tone after a few hours playing. Personally, I think strings can sound a bit clunky, brash and tinny when they first go on. I like them better after they've been played in for a few hours, and depending on the guitar, I think they can sound their best up to a week old. I actually think a string's sustain improves after a couple of day's playing on it.

Also its really worth getting into the habit of stretching your strings in properly when you first put them on. If you've noticed a new string's tendency to go out of tune constantly for the first day or so, that's simply because you haven't stretched them in. What you do is to take each string in turn (as you put them on is best - especially if you have a floating tremolo unit) and put your finger under it at the bridge end. Then you pull the string up away from the guitar (stretching it) and slide your finger all the way up to and past, the nut to the machine head. Do this two or three times, retuning the string each time if necessary, until it stops going flat. You'll find that once you've stretched them in like this, they'll stay in tune, there will be no constant tuning up for the first day or two. Note: after you've first stretched them in (depending on the guitar) the may go slightly sharp after a while, but once this is retuned, they'll stay good and stable.

A final tip: When you change your strings, don't take them all off at once, replace them one at a time (leaving the others on). Start with the low (wound) E string and work up. Its not particularly good for your guitar's neck to keep releasing the tension of the strings by taking them all off. Its fine to momentarily release the tension, as would happen if you pressed down on a tremolo arm, but to leave the tension off for 10 or 15 minutes regularly, is probably not a great idea. Obviously you have to take all the strings off occasionally to clean the fretboard. Also if you have a floating tremolo system such as a Floyd Rose or similar, you'll find it much easier to retune the guitar if you just take off one string at a time. If you take them all off, it may take you an hour to get it back in stable tune!