Tuning is really easy. Basically just waxing, filling in major scratches, sometimes sharpening edges.
It is all easy and pretty sell explainatory. I usually only fill in major base gouges as p-tex you use to fill in you bases with is slower than that on the ski. I don't keep my edges very sharp, don't really need to unless your racing.
Waxing - clean off base, drip wax on, melt wax (not too hot or you can bubble your base), scrap off, brush. Brushing is important. Basically, the more brushing you do the faster your skis will be as the water that melts between the skis base and the snow will have more channels to escape from.
Edges - on new skis detune the tips and tails some. I usually try and get rid of burs and sometimes sharpen them a little. But, as I said above, edges aren't usually a problem for me so i don't spend much time on them.
Filling in gouges - I use p-tex sticks. there are other more expensives ways (p-tex gun) but $ wise they aren't worth it for me. Get p-tex stickers and good lighter. I small lighter torch thing works best. Clean out gouge. Heat up p-tex and keep it as hot as you can. If you start seeing black it is carbon forming on the p-tex and makes the p-tex not as strong. Drip the p-tex in. If it is a really deep gouge I often do it in parts and let it set. So, I fill the gouge maybe 1/2 way, let it sit, fill gouge the rest of the way, let it sit, and then scrap. So, scrap it off, and your done.
If it is a core shot you can use epoxy to fill in the bottom. Let that sit for awhile and then cover it with p-tex.
Hope this kind of helps.