Keep it clean
Very important: Keep the tablet digitizer surface and pen tips clean and smooth!
This is true of all graphics tablets, but especially important for integrated tablet/display devices like the Wacom Cintiq devices. Why? Because you don't want to scratch the display surface by dragging dirt and dust across the digitizer with your pen or eraser. Graphics tablets are very expensive; a little preventative maintenance can keep yours working like new!
I use Kleenmaster Brillianize which leaves a very slick, smooth surface. Brillianize is available from Tap Plastics or on Amazon.
I have also used Meguiars #10 Clear Plastic Polish, available from Amazon, and some hardware or car parts and accessory stores.
I clean the display and digitizer surface (turning off the display power first!) with Brillianize, using a microfiber cloth. Polish the display using a clean microfiber cloth, until there are no streaks visible on the surface.
Pen tip cleaning
It's just as important to clean the pen and eraser tips. Use a microfiber cloth dampened with a little Brillianize, then buff the tips using a clean microfiber cloth.
After cleaning the digitizer and the pen/eraser, you won't believe the difference! It'll feel as smooth as silk. Enjoy!
How do I know when to clean the display and pen?
You'll know - the pen will start to 'drag' a bit, which may indicate that the tablet surface is accumulating dust or other debris. Just clean the digitizer and pen as described above, and you'll be good to go!
Protect Your Tablet With a Tablet Surface Cover
You can use a tablet surface cover to protect your digitizer surface, if you can find one that fits. This may not be a good option for integrated displays/tablets like the Wacom Cintiq because it may degrade the display quality.
If you use a Wacom Cintiq or similar integrated graphics tablet and display, you might want to wear white cotton gloves while you work. Why? Well, it helps keep the digitizer/display surface clean and free of oils or other contaminants that may be transferred from your skin. It also makes it easier to move your hand across the surface by reducing drag.
Some people cut off the thumb, forefinger, and index finger out of the glove, which leaves just the palm/wrist and last two fingers covered, which is enough to protect the digitizer surface while providing maximum 'feel' while holding the pen.