What abrasive setup do you recommend for tool grinding?

I find the whole abrasive thing to be incredibly confusing and expect what I am doing now is probably totally wrong. You have aluminum oxide, silicon carbide, ceramic, diamond, etc. Then there are the bonds; vitrified, rubber, etc. For grinding edges on tooling, what abrasive setup would you recommend and why?

Vitrified aluminum oxide in various colors is an inexpensive wheel for grinding HSS cutters. with 46 to 60 grit being a common grit, often in an H to M hardness.
Diamond wheels for carbide, best wet.
Name brand aluminum oxide wheels are often better than china or off-brand wheel.

A solid setup aids tool grinding. Heat can be a bugger to aneal a sharp edge. Often good to take .005 off after the edge is cool. Sometimes it can be good to grind the heal first so the primary is a tickle cut.

A Norbide stick can dress a wheel sharp corner. An Abrasive wheel roller hand dresser can be very handy for dressing OD, angle, and sharp corners.

See Crackerjack mini wheel dresser. Yes, you break the dresser wheel rpm so it turns at a reasonable RPM, perhaps less than 2000 RPM. (often turning at 300 is plenty.)

Here is a decent quality 14" Bay State 46 grit AO wheel doing an entirely satisfactory job on this HSS shell reamer

The USA high quality dressing diamond is held in this B&S #4 in its tail stock

White AO is typical for HSS, but will not cut carbide. 46-60 as mentioned. Michiganbuck mentioned H to M, I want to say K is pretty common here.

Green Silicon is typical for cutting carbide, and can cut HSS. Might use this to form or change cutter shape of tool. I'm thinking 80 to 120 grit is more common here. Finer grit if you don't need or intend to use a diamond wheel to finish.

Diamond wheel for finish edges on carbide, where needed. But you won't typically use it to shape the cutter tool.

I don't fully grasp all the bonds and hardness either. I wouldn't mind seeing eKretz response . He posted a manual a bit ago that covers basic wheel dressing and some basics that are helpful:
Norton's "For Grinder Hands Only" Wheel Dressing Manual

Or - say - grinding treading tools

I don't have a whole lot more to add over what has been said already. That was some good information from you Charlie. You can't get much better references than John or Buck either. The only thing I might ask is exactly what kind of tool grinding. That can make a significant difference to the answer you're looking for. Are we talking freehand on a bench grinder? In a T&C grinder? Round tools like reamers? Threading tools like John showed? Turning? Etc.

And use the SiC for carbide, but only for roughing. Finish with diamond if at all possible. Grinding tungsten carbide with silicon carbide is kind of like going at the job with a hammer and chisel instead of a machine tool.