I think the angle depends on the knife. I've asked similar questions, and I'll pass on what was suggested to me. Get a couple of inexpensive Moras to practice your technique with. This is especially important if you have an expensive knife that you want to protect, and not ruin. Color the cutting edge with permenant marker. This way you can see if the angle you are using is removing the metal or not. If the marker is still there when you're done, you haven't sharpened the knife. There are books and videos that give step by step instructions, though the names escape me now...one book..."How To Sharpen Everything" or something like that.

The main thing is to just practice! One of my favorite sayings is, "If you have to think about it, you don't know it well enough". Of course I don't recommend shutting off the brain while working with sharp metal objects, but I think you get the point.

Good Luck!