This is probably as old as the invention of skis, but skiing is so much more than just racing down the slope. Skiing in a straight line down back to the ski lift takes away a lot of fun (and the actual skiing). In my quest for a good guide for skiing techniques, I stumbled upon this seemingly outdated PDF of I guess beginning of the nineties. You can download it from this site for free and it comes with a lot of instruction videos too. It explains in detail; movements, parallel skiing, moguls, skiing on powder snow, possible barriers, a special section about woman and skiing, safety procedures and more. In the back, there is even a handy glossary in which technical terms are being explained (and of course we ski lovers learn this by heart as a second language). It is a generally good read and it can help a lot in understanding the basic and the more advanced techniques.