Well, here are some tips I have learned along the way.
When you are just starting out, forget using more than one mic, because using more than one can lead to phase issues. Using multiple mics is not going to make your recordings sound any more professional, but they can add a very nice flavour to the guitar tone. For example, the metal producer Andy Sneap usually uses only one SM57 on a cab, and I think he gets pretty nice results.
A good dynamic mic on the edge of the dustcap, depending on the speaker of course, very close to the grill will get you there. Some speakers are of course darker so then you might try moving the mic more to the center of the speaker. When you have achieved great results by doing that, then you might start trying out condenser room mics etc. to add some room or whatever you are after.
They key to a great guitar tone is, that you don't really need to do a lot to it after you have tracked it, except low pass at about 12khz and maybe some minor EQ:ing. Using compression on a high gain guitar track is pretty pointless, because the sound itself is usually very compressed. However, a good multi-band compressor is sometimes a good tool, when the low end of the guitar's is too boomy.
But the point is, get the tone as close to perfect as you can by tweaking the amps EQ, moving the mic etc. and then only do some minor adjustments afterwards.
When tracking metal rhythm guitars, it's usually 4 tracks panned left and right and the bass at the center.
But, in the end, there are NO rules when tracking/mixing, because "tone" is a very subjective thing, but those little tips might make things a bit easier for you.
And good monitor speakers are a good investment also. I remember listening to some stuff I had posted here, and being very ashamed, since the guitars sounded so goddamn shrill and harsh. I was using normal computer speakers then, so the guitar tracks sounded fine through 'em, but I didn't even imagine how terrible the tracks really sounded. No bottom end, only this shrill fizzy high. I wonder what people were thinking when I posted the Mesa cab/Orange cab comparison clips....
