wipe the mouse down with a washcloth dampened with disinfectant, including the thumbwheel(s), once in a while. DO NOT SPRAY THE MOUSE - you don't want that liquid getting inside on the circuit boards or interfereing with the optical parts (it could be conductive or corrosive)!
if your mouse is starting to "stick" and you are having to slam it down on the mouse pad, it's time for a cleaning:
The ball doesn't often get grimy buildup, but if it does, it fails to spin the mouse wheels. Because it gets grimy buildup, you have to clean the mouse wheels too (all 3 of them).
Routine Maintenance: unscrew the bottom cover, Remove the ball and clean it with a wet washcloth you know isn't going to shed. Scrape the grime off the wheels with a fingernail, turn the wheel so you can get at some more of the wheel, scrape, repeat until the entire wheel is done. pick out the garbage if you can and blow out the rest real hard. Do all the wheels - they all matter.
Ball Mice like to have a rough surface for the ball to roll on to get some traction - remember it's made out of rubber. a plain desk isn't a good idea. get a mouse pad. Fellowes makes a cloth-topped mouse pad with Microban that you don't have to clean.
Maintenance: nothing new to report for maintenance, you can wet a washcloth with disinfectant or detergent but DO NOT SPRAY THE BOTTOM OF THE MOUSE! it will leave spots on the optical sensor up inside the bottom (especially if it's a disinfectant or cleaner) and it's impossible to get at the surface in there to remove those spots - you might as well get a new mouse.
I am not sure you should even try using a cotton swab on the sensor/lens, because those can leave scratches on that plastic (found this out about cd-r data surfaces with the "buffing" process given by a manual).
Mouse Pads: Yes you should use a mouse pad. lighter solid colored midtone cloth mouse pads work best, such as gray, blue, green. Black does not work with optical mice. White does not work with optical mice. do not get a mouse pad with the same color as the laser in the mouse.
nothing new to report for maintenance. some are 3D. some use the gyro for features. no mouse pad required (depends on model), but it can wear your arm out & cause wrist trouble.
keyboards need to be wiped down with disinfectant once in a while too.
if you have fuzz, junk & food between the keys, try these $9 thin keyboard swabs. or an air compressor and face mask?