The day before closing your pool and if you are using chlorine tabs or an ionizer, add a regular dose of shock. (Regular dose = 1 lb per 10000 Gallons)
On the day you are going to close your pool, make sure the pool water is clear and free of leaves or other debris. (The cleaner you close it, the cleaner it will open.)
Add the winter chemical kit. For Chlorine, Salt and Ionized pools, the kit will have 3 chemicals; stain & scale preventative, winter shock, and winter algaecide.

Dissolve each chemical and add to the pool one at a time. For Polyclear, Baquacil, and Softswim pools, add a normal dose of shock and sanitizer, as well as a double dose of algaecide.

Run the Pool for 1 hour.
If you are not using a special skimmer plug or cover (I.E. a gizzmo, or aquador), you can SKIP this step!

Drain the pool 1 inch below the skimmer. The best way to drain the pool is to connect the manual vacuum and run the filter on the Waste Setting with the vacuum head resting on the floor of the pool.

Remove the eyeball from the return fitting inside the pool. Replace it with a threaded plug. (The eyeball should come out in 3 pieces, leaving an opening with threads inside it on the inside of the pool.

Sometimes only 2 pieces unthread leaving a part in the wall. A special Return Key is made to easily take this last piece out without damage.

Remove all hoses from the pool, pump, and filter by loosening the hose clamps with a screw driver or nut driver.
Remove all drain plugs from the pump and filter. (If the pump has no drain plugs, tilt it forward. If you removed the hoses as per the above instruction, all the water should pour out the hose connectors.) 
Be sure to remove the pressure gauge and sight glass from the filter. Also set the filter on the Winter setting. (If you don not have a winter setting on your filter, set the handle between two settings) If you are using an Ionizer, remove your electrodes. Take care to use the wire connectors. Unscrewing the electrode screws is not recommended.
Place the pump & hoses indoors (a shed is fine.) You may cover the filter with trash-bags to protect it from the elements. All small items (drain plugs, sight glass, etc.) should be placed in the pump basket so they don't get lost over the winter.
Float the winter cover on top of the water with enough slack to allow for expansion and rain-water. If you are using air pillows, float them to the center of the pool and secure them before putting the cover on. (More detailed instructions for putting the cover on the pool are included with the cover.) Secure the cover on the pool using the cable and winch.
During the winter, please keep water and debris off the top of the cover. Maintaining 1 inch of water on the top is OK because it will keep the wind from whipping the cover off on a windy day, but no more than that. Keeping the cover clean helps the cover last from year to year and makes opening easier. Debris can be removed with the leaf net and brush on the end of your extendable pole. Water can be siphoned off the cover with a garden hose, a sump pump, or a Cover Saver siphon pump.
Instructions for Opening
When Spring arrives and you're ready to open your pool, make sure the cover is free of water and debris. Remove and clean your cover with a garden hose. Let the cover dry then fold it and store it safely for next winter.
 Hook up the pump, filter, and hoses. Replace all drain caps, sight glass, and pressure gauge. 
Set the filter on the Filter Setting.
Remove the skimmer plug and threaded return plug.
Replace the skimmer basket and replace the eyeball. Set the eye at a roughly 45 degree angle down and away from the skimmer.
Fill the pool to the second screw on the skimmer face-plate, if necessary. Let the pool run for 24 hours, then bring roughly a 12 Oz. bottle of pool water to Best Pools!