This is a good prep that will help skis turn well and glide fast.
At the top of the course, scrape (with a plastic scraper) ice, snow, excess wax and debris off of the skis. Then brush them hard with a nylon brush. Now apply a low-fluro paste or liquid wax and follow the directions. Skis prepped in this fashion are surprisingly fast (I have measured a 2 second improvement on a 60 second SG course over dry skis)... and it is SO easy. Repeat for the second run.
The TRUE basics: Paste wax and a polishing cloth. Works like a charm.