I'm actually not sure there are "much better" methods, though I'll admit there are few that can go so wrong so quickly. I can take a knife that has no edge (as in primary grind but no edge bevel, terminating in 1/16" thick of steel) and have it shaving, with a pleasingly-even edge bevel in about five minutes. Moving to compound-loaded leather belts, I can make the edge a mirror and have it whittling hairs in about ten minutes. It comes from practice, and it took me a few years to get to that point where I don't hesitate in the least to take a many-hundred dollar custom knife (mine or somebody else's) to the grinder.
What I learned on was a bunch of cheap (like $5 a piece) machetes that I bought from a hardware store, so that I could figure out angles and movement on a belt when it didn't matter. In general:
1) Move your whole body, not your hands. Get where you're looking down at the belt contacting the edge and rock the blade through the motion. When you're moving your hands/arms too much, it's easy to change angles without meaning to.
2) I keep a thumb on the back of the blade, right down by the edge where the action is happening. When the steel moves past "luke warm" and starts becoming noticeably warm, it's time to dunk it in water. I keep a large pitcher full of water next to the grinder, along with a towel to wipe it after dunking. Getting back to the correct angle again after you've gotten out of position for dunking will come with practice and nothing but.
3) Don't let the blade linger on the belt--you're moving the whole time it's in contact. I move at about one belt's width per second when doing an edge, which (in the case of the grinder I use to sharpen) is one inch per second.
4) Just like with stones, if you have serious damage to get rid of or you are reprofiling, get the majority done with a coarse belt and only go fine when you're getting close to having the bevel completely formed. I don't move above 50 grit before an edge is sharp enough to cut skin. Finer belts generate more heat, so stay away from them until the end, during the flattening/polishing stage where you're removing the scratches from the coarse belts and knocking the "teeth" down to a reasonable size.
5) As you near an actual edge, the steel will "feather" or form a wire edge as you're going which makes it difficult to see what the bevel is doing. I keep a piece of scrap oak or maple handy to drag the edge through--these materials are soft enough for the wire edge to bite into and hard enough to tear it right off, leaving the bevel clean.
6) Always err on the side of caution, better to dunk too often than not often enough. This gets even more true when dealing with thin blades, which it's best to move across the belt even faster and dunk after every single pass as they have less steel to act as a heat sink.
7) Finishing with a microbevel on a very fine stone is often a good last touch. Achieving shaving sharp with nothing but belts is no big deal, but newsprint-shaving sharp with only belts will take a bit longer to get down, or at least it took me longer.
Edit to add: I don't recommend grinders for basic edge maintenance, except for leather belts with compound. There's no reason to remove as much steel as an abrasive belt takes off just to take a slightly dull edge back to razor sharpness. For serious work, however, (taking an idiotically-thick 40 degree included factory bevel down to a sane 25-30 degree bevel) it's hard to beat.
