Well, I haven’t tried cutting brass yet so I can’t speak to that, but for wood, I’d suggest sticking with solid carbides if you can, they’ll last a lot longer and take a lot more abuse in terms of heating. For general bits, this is the set I use.
1: 1/4" Upcut Spiral - This bit will be your workhorse! It will do profiling, pockets and most other work with ease. As long as you do not need excessive detail, this one will do it.
2: 1/4" Downcut Spiral - This bit isn’t quite as chip-clearing as the upcut, but tends to press your workpiece against the wasteboard instead of climbing, and results in very nice, clean cuts. Excellent for plywood or finishing passes, this is another workhorse.
3: 1/8" Upcut & Downcut Spirals - More or less a smaller version of #1 and #2, used for smaller parts, with the same general notes. These let you cut out smaller pieces. Have to be more careful with the feeds, though, as it’s a smaller bit. Still very robust.
4: 1/16th Upcut Spiral - Great little detail bit, the ‘fishtail’ ones are superb for clean work in lettering and soforth. Be gentle with it, this bit breaks easily.
5: 1/4", 1/8" and 1/16" Ball Nose - These will be used for 3D profiling. If you’re not doing 3d work, you do not need these at all. If you are, they are absolutely necessary. Again, go careful on that 1/16th bit, it’s fragile.
6: 1/4" 60-degree V-point - If you have V-carve, this is your workhorse again. Will do almost any kind of V-carving quickly and well!
OPTIONAL: I don’t use this one but very, very seldom since I have a good planer, but if you don’t, a 3/4" two-flute “straight” router bit might be very handy for you. It’s good for planing and leveling the top of your workpiece, and cutting to thickness. Your X-Carve needs to be VERY square and straight to get good results from this bit, as far as I can tell, since the width means that even a slight miss-alignment will leave a slight step between cuts. It makes a good wasteboard cutter too, for setting up precision sub-wasteboards.