Here's some more tips I've figured out with PSP X2 & X3:
If the skin smoothing isn't smoothing enough, try the one step noise removal (even if you don't have noise) and then smooth the skin.
I always sharpen the eyes of my subjects just a little
I find that the smart photo fix always tries to add too much brightness, and hardly ever adds saturation. I almost always bump the brightness down 10 and the color up 10.
The scratch remover is an awesome tool! You can use it to remove hair from a face, telephone poles and lines, stretch marks on pregnant women, and so much more. If the blemish fixer is giving you unfavorable results no matter how you set it, try the scratch remover.
Any area that I edit that isn't the main subject of the photograph, or if i want a smooth appearance, i use the smoothing tool, it covers up editing marks quite well.
Want to remove something unwanted from the background? The clone tool is great for that, just takes some playing around with it to get it right.
The toothbrush is an awesome little tool, you just have to play with it a lot. Watch out for it making the whole face white instead of just the teeth. If you're looking for the vampire look though, bump it up a bit and it'll add a neat ghostly white appearance to the face.
Almost every picture I touch up I always use the brightness and contrast under the adjust tab. I usually do this last and leave brightness on 0 and add about 4-8 on to the contrast.