1) Select the proper wax for the job. A warm weather wax is softer, while a cold weather wax is harder. Wax is categorized by temperature. This is in reference to the air temperature, not the snow.
2) Clean the base with a base cleaner.
3) With the iron on a mid-level setting, apply the wax by melting it against the hot iron, dripping beads of wax along the full length of the base. If the wax smokes heavily against the iron, lower the heat setting.
4) Iron in the wax by placing the iron directly on the base while moving it quickly in a circular motion to avoid singing the base. As the wax melts, work down the length of the base and back up making sure not to miss any spots. You may choose not to wax the tip and tail each time you do the base because these areas will not come in contact with the snow as much. This will also better assure that the board will not kick out from under you if you land on one of the ends, and you won't have to buy wax as often.
5) Wait at least a half-hour for the wax to cool. When the wax is cool, scrape off all the excess with a plastic scraper using short strokes from the tip to tail. Next, use a few long strokes from tip to tail to finish the job. This will leave only a thin coat of wax remaining. Keep in mind that the reason you wax your base is not to have a lot of wax on the base, but to get the wax saturated into the base. Otherwise, the base will become dry, brittle, and slow.
6) Buff in the wax using cork or a clean cloth, working with brisk strokes from tip to tail.
7) From the tip to tail use a nylon brush or Scotch Brite pad to add structure to the wax. This will break up the smoothness of the wax, thus helping to reduce the suction between the base and snow.