I guess I need to throw out some tips along with my general "practice makes perfect" statement

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Use a gentle, but firm touch. If you just float the knife on the belt, you will not get a consistent grind. Also, if you push too hard, you'll make mistakes.
Let the belt do the work, but control where the belt works. Watch where the sparks are coming from on the belt. Are they coming from the edge or from the middle. Try to keep them in the middle of the belt until you have more control with what you're doing. You'll eventually learn what it feels like to grind in the middle vs. the edge and when to use what part of the belt.
Lock your elbows down to your side. Develop a consistent stance and uses your body movements more so than your arm movements. Keep a water bucket under your platen so all you have to do is reach down to dunk the blade. Keep it cool. A hot blade will cause you to hurry or to jump.
Have good lighting at your grinder.
I grind edge-up. Watch the junction of the edge and the belt. You'll be able to tell where on your blade you are grindng by the space between the edge/belt.
Don't grind your bevel all at once. In other words, it doesn't start at the same angle that it finishes. Start with a 45 degree bevel on the edge that takes you down almost all the way to your desired edge thickness. Then walk that bevel up the blade towards the spine.
Use a height guage or edge scribe to mark your blank before grinding. You can either mark the center line, or as I do, mark two lines about 1/32" apart form each other. This keeps your edge centered and gives you a reference as to where you need to take more steel off.
To avoid the 2" line, you'll eventually learn to very subtely lift the tip-side of the blade as you move into the plunge area. This takes practice to avoid carving a gouge in your plunge. Until then, focus on keeping the sparks in the middle of the belt and not stopping in any one area.
Hopefully, these tips can help you out a bit. Good luck and happy grinding!
--nathan