I’ve helped a few people to sharpen, there are a few things that usually are the root cause of difficulties.
First off there has been superb advice by
@Jacob and
@Cabinetman take it to heart. Sharpening isn’t difficult.
The first problem that usually causes problems is that the chisel (let’s start with that) has after repeated tries to sharpen developed a convex slope on the chamfer. This has been caused by rocking when trying to hand sharpen. This makes trying to get it sharp very difficult, as once it’s convex, you will rock even more and little of the effort is going to grind the tip.
The back isn’t flat at the edge. Ignore all the suggestions of getting the chisel back flat along its entire length. It just needs to be flat where you’re sharpening.
Thirdly trying to sharpen with a very narrow chisel: which usually causes side to side rocking and further convex shaping.
So where to start. First off a black sharpie is your friend. Cover the chamfer and about 12mm of the back of a chisel that’s around 20 to 25mm wide. Place chisel on course media and try to flatten the back about 12mm from the edge you want to sharpen. Give it about four or five rubs and then see what’s happening. The black will have worn away where you’re touching the media. You now have a guide to see what you’re doing. If you push back and forth in just one direction you will create a convex surface, so keep changing the direction, it will also cut faster. Re jacket and keep checking.
Now when you’ve achieved a nice shiny surface about 2mm back from the edge, all the way across, repeat with higher grits, blacked and check you get a shine across the edge. The back is now ready.
Now, blacken the chamfer. Using the roughest media and sharpen by placing the heel on the media, rotating until the chamfer is down on the media and pull back, lift off and look at what you’ve done. If it’s concave you will see it. Repeat, only dragging back, never push and pull when learning, you will cause it to become convex. Continue until you have the full chamfer shiny right to the tip. Check for a wire bead, quick few strokes on the back to remove the wire, and rinse and repeat with higher grits.
To get it to cut hair it needs stropping. But it’s not necessary for use. Be careful it’s now very sharp!