Waxing Basics.
The three things you need to know.

1. You need to have good bases.
2. You need to know your waxing iron.
3. The waxing process itself.

In order to wax your skis, you need to have a good base prep. Most skis have really rough bases with lots of microscopic P-Tex hairs that really slow you down. Likewise, a too-hot iron (see Item #2) will seal over the P-Tex bases, not allowing any wax to really soak into the ski. If your bases have a dry, white powdery look to them after just one day of skiing, you have sealed bases.
What fixes sealed or rough bases? Elbow grease. There are many great articles on this subject, one at the Star Wax website and another at Toko Wax. Basically, you take sandpaper to take off the top thin layer of P-Tex, once again opening up the pores. Then you scrape the ski to shave off as many of those tiny hairs you just made when you sandpapered it.
If you live in California you want to use a coarse sandpaper, because while you are opening up the bases, you are also creating some structure. Perfect flat, smooth skis create a suction on the snow so a base with some sort of linear texture to break up this suction is the goal. So open up the pores, create some structure and eliminate the P-Tex hairies is the overall plan for base prep. Luckily this really only has to be done once (unless you are racing) provided you don't use a overheated iron to seal the base pores back up again...

2. A good iron.

The more I play with waxing skis the more I see the important of a good iron. It's okay to use an iron you found at a garage sale for $2.00, but be careful! You need to calibrate the iron and the dial probably isn't even close to the real temperature. Here's the problem -- you need a iron hot enough to melt the wax and warm the base, but you don't want it too hot or it will seal up your bases. P-Tex melts at around 275° F (135° C) and the ideal temperature for bases to absorb wax is around 110°-120° C.  That's a rather slim margin of safety between good wax absorption and sealing up the bases.
And when you take a household iron and apply it to the ski base, the base "sucks" the heat out of the iron, the temperature drops and all of sudden it seems like it's not doing a very good job -- so naturally, you turn it up. The trouble is, household irons have such a wide temperature range that it has to drop a long way before it clicks on and starts to warm the iron. The least expensive way to check a cheap iron is to buy a dial thermometer (Tognar Toolworks has them for $7.95). You let the iron warm up, put the thermometer on it and watch it while the iron cycles through it's temperature range. There's nothing wrong with using a cheap iron for waxing, but you better be sure it's not so hot it seals up your bases or you have a lot of work ahead of you.

3. The waxing process itself.

Okay, so you took some time to completely rehab your bases (it is about a half a six pack of root-beer job), you got a thermometer for your iron and watched it go up and down a dozen times and are sure your iron is ready to do the job. Now what?
I assume you have some glide wax. Again, for California you can probably get away with only one glide wax -- our temperature are so consistent. I personally use Swix CH-8 or LF-8 for all my skis. CH-8 is a hydrocarbon wax, is an inexpensive wax (a 60 gr tub is about $7.00) and should last you about one season. By the way, the LF stands for lo fluoro and has better water repellancy, wider temperature range and is a faster wax. By comparison, a 60 gr tub sells for about $18. There are many brands of wax -- Toko, Star, Swix, Dominator, etc.), just pick one and stick with it.
So you've got the wax, the iron is hot and you're ready to rumble. Hold the wax to the iron base and drip some "dots" up and down the bases (If these are skis you are going to put a kicker or grip wax on, don't put glide wax in the center portion of the ski). Once you get some wax on, start heating the wax into the base. The secret here is to get the entire ski base up to temperature so the wax can really soak down into the base, but not so hot you seal the bases over. If you bought that thermometer like I told you, you wouldn't be worrying about it right now.
Once you get the base nice and warm and you have lots of wax soaked into the base, let them cool awhile until the wax has hardened, but is still warm. Then take your plastic scraper (again, Tognar Toolworks makes their living from selling only ski tools and waxes) and going from tip to tail, scrape off the excess wax. The bases are harder than the scraper and the scraper is harder than the wax, so do a good job.
Once you get all the wax scraped off, take a 3M Scotchbrite (fibertex) pad (you know, those green and yellow sponges) and use the green side to burnish the ski. Then consider applying more wax and scraping it again. New bases should be done at least three times. The big secret is everytime you do this you are scraping and fibertexing off more of those tiny polyethylene hairs and making your ski faster every time.
After you are done waxing, scraping and fibertexing, take a nylon brush (buy a cheap one and work your way up to an expensive Swix brush) and brush the heck out of the base. The idea is to get any wax out of the structure. You need the proper wax to "balance" against any snow condition, but you don't want the wax to interfere with the structure of the base. Brush, brush, brush.
After you go through the entire process of prepping your bases, calibrating your iron and waxing your skis, you should only have to wax, scrape and brush when your bases start looking really dirty or dry.
At the end of the season, apply a thick coat of wax and don't scrape it off. It's a great way to protect your bases against oxidation over the summer.