1. Take your basecoat surf wax and bring it across the board from rail to rail. Start at the tail and work your way up, slightly overlapping as you move upwards. Apply enough pressure to leave a layer of wax as you move.
2. Once you get to the top of your wax area (all the way to the nose for long boards), change directions and do a perpendicular layer of basecoat lengthwise, drawing it from the tail to the nose. Move your way across the board, overlapping again. There should now be wax bumps on the board.
3. With a wax comb (a plastic hair comb will work in a pinch), score the basecoat at a 45º angle, again moving bottom to top, then do a criss-cross. This will give the top coat something to “bite” into.
4. Determine the temperature of wax you’ll need. Colder wax is softer and tackier, but will melt off in warmer water conditions. Warmer wax is harder but heartier, best for temperatures from 65-75ºF
5. Using a small circular motion, apply the wax to the basecoat, moving from bottom to top. The top coat will stick to the wax bumps and score marks.
6. Lightly apply some to the edges of the board for help gripping the board in the water.
To remove wax, warm it up by allowing the board to sit shortly in the sun or using warm water. Scrape the warmed, soft wax with the scraper side of the wax comb (or use a credit card).
Wikihow has some great tips, and this video shows all the steps in detail.