The advice I was given when I started a year and some change ago, I've pasted this one around in quite a few places.
The go-to guy around here is Doug Rising, he both supplies the Trizact belts, and can answer darn near any question you'd ever have. He's really easy to talk to as well, just drop him a PT. You'll be amazed how easily your knives gain an awesome edge with the belt, it's what I use for the bit of sharpening I do down at a local gun shop, and the edges never fail to impress.
To answer your question:
To start out with I will give you the same advice I received from Doug when I started out. I would probably get some inexpensive grit belts. EconAbrasives has very good deals, I would probably purchase two each of 120, 220, 320 and 400 grit, then add a 15u and 9u micron-graded belt. Also, two SurgiSharp leather belts, and a pound bar each of their green Ultra Fine and white Extra Fine buffing compounds. That will get you started with a fairly minimal investment, and will easily put VERY good edges on your blades. Once you're comfortable with the belt and have decided that you're going to keep that as your sharpening method, then talk to Doug, and let him guide you down the rabbit hole of the Trizact family. They're really superb belts, and are well worth the higher price tag once you are comfortable with sharpening on your new tool.
I personally have been sharpening on the belt for only a year and some change now, and am still learning a lot with every knife I do. I just know I won't be going back any time soon, certainly not for working edges!
If you're interested: My current line-up runs a Norton Blaze ceramic 120-grit belt if the knife needs a little re-profiling, chips removed or a tip reground, then Trizacts in A65, A20, A16, A6 and A3, then the same two SurgiSharp leather belts I started out with, and the Econ compounds. Depends on what I'm doing, but frequently for working knives I will use the 120, then the A65 and A16, then the leather. I've actually run with a 120/A20/Leather set a couple times for fairly good results, but your mileage will vary with your style, and what kind of edge you decide you need.
I would HIGHLY suggest just going and grabbing some cheap old kitchen knives from a second-hand store or goodwill to practice on, that way if you get a little grind-happy and take off a tip while you're learning, it's no biggie.
General tips:
1. Keep it cool! If you can't pinch the edge tightly in your fingers as soon as it comes off the belt, you're getting a tad warm and it's time to dip the blade.
2. Only take the point HALFWAY across the belt. If you drag the point all the way across, you can take it right off the knife in an instant.
3. Light pressure! The belt is doing the work, your job is just to guide the edge along it.
4. Keep the edge square to the belt. You always want the belt moving so that the grit is passing perpendicular to the edge. That means as the belly and tip roll up toward the spine, you will need to lift the handle to keep the edge parallel with the floor.
5. Don't stress! The belt is a very instinctive way to sharpen, and convex edges are quite forgiving. Don't worry about angles too much, it's very easy to see if you're getting things even by looking at how far the spine and belt are apart.
EDIT: For meat slicing, your best bet might be to stop at a 220 grit belt, and just use the green on leather to strop off the burr. A little bit of bite left in your edge can make the slice through tissue a lot smoother. The downside is that it dulls more rapidly than a highly-polished edge, but if you've got the belt right there, a new edge takes about 90 seconds.
