CLEANING YOUR CELLO
Your cello should be dusted off once a week, or just before a performance. Use a slightly damp (with water) cotton cloth. If you have rosin build up that won't come off with a damp cloth, use a very small amount of commercial violin polish. Do not spray your cello with silicone or wax. "Less is more."
STORING YOUR CELLO
You should keep your cello in a place where it will be away from children, and not likely to be knocked in the normal round of household living. It is not necessary to put your cello in its case, unless you will be traveling with it. In fact, putting the cello in and out of its case more often than necessary will lead to unwanted scratches. On the other hand, if the place where you keep your cello is full of unruly children or pets, you may want to keep your cello in a hard case whenever it is not in use. If you will be away from your cello for several weeks or months, it may be wise to loosen the strings a little bit, but not all the way, lest the bridge fall off.
You should examine the bridge once a week to make sure that it is nearly perpendicular to the belly of the cello. If it slants too much it could snap in half, or be pulled over by the tension of the strings. You may adjust the bridge by loosening the strings slightly and grasping the bridge firmly with both hands, moving it into correct position. The feet of the bridge should fit flush on the belly of the cello, centered between the f holes, and approximately in line with the notches in the f holes.
When you set your cello down, make sure the endpin is not sticking out where some careless person may kick it accidentally and send your cello flying. Some cellists sharpen the endpin to a fine point and stick it in the wood floor or carpet when they perform. This may be dangerous, and is bad for the floor. Instead I recommend an endpin holder with an adjustable strap, such as the Xeros Anchor, which may be purchased from many string shops for about $10 US.
Keep your bow in a safe place. Don't leave it where it may be sat upon or knocked to the floor. If you have a soft cello case, you should insert a pvc pipe into the bow holding pocket, just large enough for your bow, and this will protect your bow from a nasty knock when you are traveling. Do not engage in pretend sword fights with other cellists. Do not tap your bow on your music stand as a form of applause. You may very easily crack or break your bow. When the music says "col legno," use a cheap bow, not your good one. You can get a cheap Glasser bow for about $40 for such rare occasions. You should clean your bow in the same way you clean your cello. Loosen the tension on your bow when you are not using it. Never over-tighten your bow. Make it just tight enough that when you play the hair does not normally touch the bow stick, but almost.
People who clean their strings more than once a week are much too picky. Clean the rosin off your strings about once a month with a cloth with a little alcohol on it. If you miss a month it's no big deal. BE VERY CAREFUL NOT TO GET ANY ALCOHOL ON YOUR CELLO!!!! It will eat the varnish. If you rarely play in public, you don't need to change a string unless it appears to be starting to break. If you perform more often, you should replace all your strings once a year in order to prevent a string breaking unexpectedly in a performance. Change strings one at a time, without loosening the other three. Don't put a gut or nylon string (even if it wound with metal) in a fine tuner, it will break the string. Always keep an extra set of strings on hand, just in case. Don't play with your strings too high or low from the fingerboard. Too high and you will have to use too much strength to press down the strings. Too low and the strings will buzz on the fingerboard. At the end of the fingerboard, near the bridge, the strings should be about 3/8 of an inch above the fingerboard.
There is no substitute for pegs that fit well. If they don't fit well, your pegs will either slip or stick. It doesn't help much to use chalk or peg slipping compound. Find a luthier to ream out the holes for your pegs, and make them work right. Gut or nylon strings may be fine tuned with the pegs alone, but steel strings require fine-tuners on the tail piece.
Over the years some scratching is inevitable, so don't get too upset over a small scratch! Small scratches should just be left alone. If you have a very large nasty looking scratch, take your cello to a good luthier to be touched up. If your cello is a cheap student instrument, it doesn't really matter too much what you do to it. If it is an expensive antique, leave it for experts.
It is not possible for the average cellist to fix a crack. Your cello may crack in the seams, or anywhere. Take it to a good luthier to be repaired.
Weather, temperature and level of humidity affect every cello. Cracks may develop from either high or low humidity. A good expensive cello should not be used outdoors. Keep your cello at home in a room with a level temperature and humidity, if possible. Some cellist place humidifiers inside their cellos, through the f holes, but these are not really necessary or very effective. Get your cello a thick padded case that will help moderate temperature changes when you travel with it.
If you travel by yourself, you may get by with a soft case. Get one with lots of thick padding to moderate temperature changes. But if you go on tours with your orchestra, and your cello is stashed away somewhere with other instruments, they will move around, and your cello may be damaged unless it is in a hard case. Hard cases are heavier than bags, so get one with wheels. It doesn't matter if it costs $200 or $2000, as long as it is hard on the outside, and grips your cello firmly on the inside. It should also have a place where you can carry a large music folder.