Hi folks,
  In all this years of practice, training, jamming & gigging i've come with a question for all of you... what's the most difficult thing you've come to face in the guitar world? ...From all the experience i've gattered in tone, music, technique & other instruments i have come to one aspect that really afect all... INSTRUMENT CARE. Really; the care you put in your instrument afects directly the handling and performance of the instrument overall. You can call me naive but i has put this to practice "recently"(from 7-8 years ago). I had always wipe my guitar after every use, clean the strings, clean the "face" of the guitar in every string change etc. but that's not enough. 90%(or more) of guitarist & bassist out there get used to do the same way i did and think they're doing great... but in a couple months realize that the tremolo/bridge is kind of getting rusted, the back plate also's getting tarnished, the pickups sound's "not so hot" anymore, hums, clicks & buzzes in the volume/tone pots & switch, pops in the line jack, etc. and think of buying a new one without realizing that most of the problems can be resolve by a in-depth mantainance.
  I always carries or have home basic equipment as screwdrivers, hex drives, cleaning cloths, polishing sprays, string degreasers, spare strings, string winders, pliers, etc. but also use other tools, less concentrated to guitar but that makes the work, like: compess air canisters, furniture oil, neem oil(used for bonsai tools; won't rust metals), spark plugs calibrator(???), cotonned tips sticks(Q tips or so), non abrasive metal polishers, 1" brushes, etc. depending in what i have to do. I will give now a quick review of what is best to know and do to keep your instrument in top notch.
 *Clean and dry your hands before playing your instrument.
 *Always clean & degrease the stings before & after any use. Never use the same cloth for strings & for cleaning/polish the guitar's body. Never use cleansers/oils/ in your guitar body/neck that isn't for this purpose. WD-40 will promote rust in your strings/metal parts... don't use it. Instead use string cleansers promoted for this use.
 *I use "neem oil" in most mechanical parts of the guitar(tuners, tremolo, etc.) because is proven to manage/prevent rust. I apply it everywhere using the Q-tips. Wipe any excess oil from the parts(apply the oils after cleaning the parts/areas).
 *Use furniture oil for the fingerboard, other oils/solubles may cause damage to the finish and wood. Again use a cloth only for this purpose and never saturated the fingerboard wet, even with the correct oil, it will promote bending of the neck.
 *Never leave your guitar tuned. It will also promote neck bending and the strings will last less. Don't have to detuned till the string only buzz but at least 2 complete rounds to the tuners will do.
 *Try not to apply eccess technique to strings; will last longer if you're carefull.
 *Reach & clean the most difficult areas of the guitar looking for filth/dust like beneath the tremolo parts, cavities, pickups & electronics. Here is where the 1" brush and the compress air comes handy. Brush the most you can with the brush, then use the compress air to virtually blow away anything that's left behind. **Watch out with the electronics; the cannister compresed air will turn to water by condensation when in contact with "hotter air", i sugest the use of an air compressor if you have access to one.
 *Keep the guitar's line connector squeeky clean; also polish n' wipe clean the 1/4" guitar cable jacks(invest in high quality cables).
 *Look for arching in the guitar neck; depress the first & last frets with both hands of any string; check if the strings keep touching all frets or some areas where the strings don't touch at all. this metod will reveal "slight bowing" of the neck. This can be adjust with the "trust rod"; I actually don't tamper with this for obvious reasons.
 *Set the strings to your desire action. Not everybody use the extreme low action seting; try and set as you think work better for you. I preffer to set the guitar action to a medium low, this is most common for any style. Low action will help playability, feels faster as you clear tones in less time with less force but afects tone directly; notes will ring less, more near to a buzz. Higher action will improve tone, everything will sound preaty clear no matter where in the neck, but playability will feel more dificult, more force needed to press the frets. For most cases, try lowering the action in the tremolo; keep checking the strings by playing every single note. When low enough to buzz, start raising the strings again by little increments till little or no buzz is heard at any note; do this with an amp; preaty low action 'cause some buzzing that the amp will not register, thus, keeping the strings very low. But is your choice.
 *To set the pickups to a maximun conduction pull the pickups as near toward the strings as posible. Play the strings one by one in the LAST FRET; if the string touch the pickup, back it down a little until the string no longer touch it. Do this procedure for every string. With the "spark plug calibrator" meassure the distance between the pickups & strings depresed at the last fret; i set it with the 1.5mm or 2mm measure. This will keep the pickups far anough from touching the strings but close enough to pick anything you do(also check by palm mutting the strings in the bridge).
 *If you do your own spare changes of electronic parts(ie, pickups, pots, etc.) try to  make clean solderings, also to use as less soldering lead as you can. The eccess lead will give the circuit more resistance thus, impare your instrument sound. Also, keep the equipment well grounded.
 *Apply the same atitude towards your sound gear & equipment.
 *Check your instrument intonation;
before you change the strings, check what stings are the one the instument came with, at least the gauge. If you changed the strings for other brand & upgraded/lessens the string gauge your guitar needs a new intonation. You'll know by playing a note in any string, then playing the same note one octave higher in the same string(e.g. play the 3rd string, 5th fret(C); then play the 17th fret in the same sting(C); try to use same pick force & depress with equal strenght both notes; hear the pitch, it should sound the same(an octave higher); if not your guitar intonation need to be fixed. This is a clasical problem in most cases. Floating tremolos are very dificult to deal with and need specialized tools. For fulcrum tremolos, bridges, etc. all you need is a screwdriver and a cromatic tuner(if the tuner can read in "cents" better). Use new strings to proceed; tune the guitar to your choice tunning. When tuned completely, play the 1st string, 12 fret; check the pitch in the tuner. Then play the 1st string, 12 fret NATURAL HARMONIC; the pitch should be the same in the tuner... Now:
 *IF THE PITCH OF THE HARMONIC IS FLATER THAN THE FRETED NOTE, make the string longer by rotating the saddle's back screw clockwise(the saddle should be pulling away in relation to the nut). This is very sensitive; a quarter of a turn is enough to make a noticiable change. Now, re-tune the string and try again; both freted note & harmonic should read as close as possible in the tuner(that's why a tuner in cents is better; 1 cent is actualy 1/100 of semi-tone, so this will tune to a more accurate pitch). Go string by string, same procedure. Remember, don't change the strings brand/gauge from now on or the intonation will need to be set again; also tune always to the same pitch. Different tunings will afect the setings you've made.
 *Obviously if the harmonic is sharper than the freted note, you must make the string lenght shorter & ressume as before.
Put real concentration while doing this 'cause the intonation can end up worst than it is if you mess up; if you don't feel to it but realize that your instrument intonation is off, seek profesional help(as i do with bended necks).
  Well, this are some of my pointers for servicing your guitar/bass yourself. Some of those should be taken daily as string & overall guitar cleaning, etc., others weekly like in-deepth cleaning of the parts/cavities etc. & others should be set to stay, like string action, pickup/strings set up, intonation, etc. as long as you keep the same strings brand/gauge profile (is good to check from time to time those settings too just in case).
  All settings should be done with the guitar tuned to your liking; the change of string action for example, will change the tune of your guitar, so, you must precisely tune first, then make the setting and fine tune again; this will change the settings you first do; check the results and adjust as need it.
Hope this is of some help, and make you realize that this info is usefull in part if not in whole. Start taking care of those instruments, remember, is a part of you, and this way you can use it to the most. Have a great day and good luck.