Well to start things off alot of people experince things such as losing picks, cables not working due to guitarists/bassists leaving the cable in the jack, blown out speakers, broken strings due to hard playing etc, and putting the guitar/bass up against the amplifer coming back and its on the floor, neck all cracked and destoryed.
Well those are some examples of the terrible things guitarist's and bassist's do on a regular basis, and when this bad event does occur, they forget it happened and everything starts all over again.
Pick Organizing: I know it's hard, but try your best not to lose your picks, when your done playing, put them in a place such as a cup or a coffe mug for instance. That way you can save money on a vet bill considering your dog eats guitar picks, or just put them in a cup or mug as stated before, an put the cup or any other thing you may use next to your amp or guitars. Picks are almost always lost, nothing you can really do, but hey, thats a small tip for some people who keep going to guitar center or sam ash every weekend for new picks and such.
Take Your Cable Out Of Your Guitar! Alot of people i talked to through the years keep their cables in there guitar while playing, and stand the guitar/bass up against the amp, not knowing the damage your doing to the guitar input jack and the cable itself. I even made this mistake alot of times, making trips to the music store and letting them fix it for you is not always fun, so please take all cables out of the input jacks. Hang your cables up somewere when your done, this can also reduce the cable from becoming tangled and distorted.
Dont Turn The Volume All The Way Up: Unless your Steve Vai or Mark Tremonti, not everyone wants to hear you playing. And obviously not to burn or blow the speaker(s) out. Put it at a level which you can hear it perfectly, not loud enough to blow peoples ears off.
Put Your Guitar On A Stand When Done Playing: Or for some hang it back on the wall. This is the most obvious one, but dont put your Gibson Custom Shop Les Paul against the amp, i know, i know, it will only be a few seconds till you play again, but it can be that fast till you see a nice crack in the neck or another horrfic sight. If your playing, and want to stop for only a short time, lay it down on a bed, carpet, or support it with a pillow at the headstock, and a pillow at the end of the body.
Don't Keep Strings On For 8 Months At A Time: Unless you have strings made from God, try your best not to keep them on for a while. Its not good for the neck, and obviously the guitar/bass will sound terrible, and future tuning problems may occur. When the first time your strings sound " dull " or not as bright as you got them, either clean them, boil them in water, or best of all change them! Now for us bassist's, its not always fun considering bass strings are more expensive then guitar strings.
Clean Your Guitar/bass Every So Often: Title says it all, clean your instrument! Residue and build up can get near the nut and in the frets producing a terrible sound. Stores sell guitar polish, fretboard cleaner, and other " methods " of cleaning. Try cleaning it only as much as you can, the fretboard can get annoying because you have to take all the strings off, and such. But hey, deal with it, it will sound better than it did 20 minutes ago!
Have A Sturdy Strap: A short portion of this article, but might be one of the most important, have a sturdy strap, i've seen people, kids, adults in general, who had weak un-reliable straps, which always fell and you guess what happens when they fall. Not a fun experince or not a nice sight at all.
Sure, some people get a strap designed by Joe Satriani, with sturdyness and very cool graphics. But some people buy straps beacuse of looks, not beacuse of how reliable they will be. So please try straps on your guitar/bass and see how they work!
This article is very basic, and consists of alot of common sense. But theres always people who dont take care of their instruments as well as they should be, and i would like to dedicate this whole entire article to them. Hope it helped some people in ways of maintaing a " healthy" rig.