ok.....first thing you wanna do is take a true bar to see if the skis are perfectly flat. ALOT of skis come from the factory concave ( the base is underthe edges), or convex ( the base is higher then the edges). To put a true bar all along the base of the skis at alots of different points, then with the true bar on the base.....hold it up to the light. If you see light at the edges.......then it is convex, and if you see the centre it is concave.
Next clean your base with a Kuu, Swix, Toko base cleaner. ( i like to use Kuu, its a great canadian product.....and cheeper).
So depending on the condition of the ski, you will either do a base grind if the ski is convex, or edge file is your base was concave.
Now most people don't have a base grinder, so you need to bring your sticks to a shop to have that done. What this will do is it will create small dimples, and cuts into your base. Wax will then fill up these holes. No matter what kind of ski or board you have......at the begining of the season you will have to do this step.
If your base was concave, you will want to sharpen your edges so they can be flat to the base.
After your done this, clean your base again.
Then your going to want to hot wax your skis. All conditon wax is the cheepest, and Fluoro wax is the most expensive AND NEEDS TO BE DONE WITH A BREATHER/GAS MASK.
If your a beginner, your going to want one of those "auto heat" irons. Plug in your iron and let it heat up. Take your wax block and drip it on your skis......and don't be stingy. After the wax is on your ski, spread your wax evenly with your iron from tip to tail. Now don't leave your iron too long in one place. Keep doing this untill the wax looks even.
The next step is to scrape the wax untill all the bumps are gone, and all you have is a nice smooth base. Use a PLASTIC scraper for this, metal scrapers are for your base.
Then take the plastic scraper to your edges, and make sure there is no wax on them. To tell just scrape your nail across them, if wax comes up....keep scraping the edges.
So many pros, and skiers forget to tune their skis. When you wax properly you can double your speed on the snow, not catch on rails, and protect your base.