You can find numerous youtube videos that show proper knife sharpening technique. Myself, I use two whetstones, one at 600 grit, then one at 1200 grit to finish. This won't get my knife as sharp as some of our knife gurus want, but sharp enough to slice through a tomato with no pressure applied but the weight of the blade.
There are a number of edges that can be used, depending on what the knife will be used for. Multiple bevels can be used to strengthen the edge, or you can create a convex bevel which creates a very sharp, and strong edge. A chisel bevel is cutting food such as sushi, or anywhere that you want the slice to be straight vertical. While normal bevels can also be used to make straight, vertical cuts, you have to angle the knife slightly to get it to track straight, and no wander out of the food.
A compound bevel on both sides is usually made by sharpening at around 15 to 17 degrees initially, then 20 degrees on the edge, creating a steeper and stronger bevel that won't turn over as easily.
there are people who sharpen at extremely shallow edges to create razor-sharp knives, using no greater than 6 to 10 degree angles. These knives (like a straight razor) are used for special purposes that don't subject them to chopping, or cutting through hard materials, such as winter squash, rutabagas, etc.
Though harder steels retain there edge longer, they are more brittle and are susceptible to edge chipping, and so they still need to have a steep enough edge to give them strength.
Here is a good URL that talks about sharpening knives -
Detailed Discussion on Knife Sharpening Angles
Here's another one that explains the advantages of a convex edge over a straight edge, it's a bit long. -
https://www.youtube.com/watch?v=iZSjeqGeo7Q
Lastly, her's another explanation of knife grinds from Lansky -
Lansky Sharpeners :: Knife Edge Grinds and Uses
My knives all have convex edges and cut very well, except for my Chicago cutlery knives that came with a hollow grind. they are good for slicing, but perform poorly if I'm cutting something with a hard rind, or skin.
That's my take on knife sharpening, for what it's worth. Others will agree or disagree based on their own experience, and what they use their knives for.
Oh, and once established, the hollow grind knife is most easily sharpened on a leather strop, where the strop is impregnated with a shapening compound, and the knife edge dragged backward against the strop. The soft leather naturally forms a convex edge on the blade edge.
Seeeeeeya; Chief Longwind of the North