I could write pages on waxing technique. I used to (ski) race for Atomic Canada, ran my own tuning business for 3 yrs, and have been on snow for the past 18yrs of my life.
As a recreational enthusist, you don't need to worry about expensive wax. The most important thing to remember is that your base is like a sponge. The more you wax it, the more wax your board will soak up. I don't mean applying massive amounts of wax at one time. I'm refering to frequency of waxing.
Getting back on track, Kuu, Swix, Briko, etc... will all tell you their products are the best. This doesn't matter for most people. If you ask at a decent shop if they have any "shop wax" for sale this is the best way to go. Basically it's really big pieces (gold bar sized) of wax. You should be able to get it for $10-20 a bar(note one bar will last all season even if you wax everyday).
Typically bars come in 4 colours depending on type of wax.
Yellow Wax is the softest and best for warmer conditions (1 to -5)
Red Wax is medium temperature range, and will be your best bet if only choosing one wax. (-3 to -13)
Green or Blue Wax is the hardest and for temperatures below -13
*note, teperature ranges are approximated, but again, for weekend conventional use this guide will do.
Getting back to your question, if you left your board for the summer without wax coating the base you'll probably notice it looks dry and white(think of it like dry skin). Take an iron(with no holes in it!!!!) and drip wax all over it and spread around with the iron.
While still hot, scrape the wax off. This will help remove the dirt from your base. Repeat as necessary (scrapings shouldn't be too dark anymore).
Every other time, let the wax cool (wait at least half hour) before scraping. The more frequently you wax your board the better as the base will become permiated with wax.
Smile suggested brushing the bass with a "wire brush" when you're finished the process. Great suggestion. Kuu sells brass brushes or nylon. Brush from tip to tail of base. The warmer the snow the more of an angle you should apply.
How/why this works: When your base travels over snow, the friction causes the snow to break down into water molecules. The warmer the snow the earlier it turns into water. Brushing prevents that suction you get when you set a glass on a table of water. This is also why wax ment for warmer temperature is softer, cold snow has less moisture and thus is harder on your base, so a harder wax protects your base.
I realize this post is a lot longer than I ment it to be, if anybody has any questions about tuning, just send a PM and I'll gladly reply.