It’s real simple: get a flashlight. Put it right up against the grill. place a 57 dead center on the speaker, right against the grill. Listen to all 4 speakers in this position ( if it’s a 4x12 obviously) record a couple clips of each speaker micd dead center. Pick your favorite speaker. Now start moving the mic to the left or to the right. Both sides will sound extremely different from eachother, although both sides will be darker the farther away you move from the center. This is important to remember, as it is often forgotten how different each side can be. SLOWLY move the mic in either direction you choose. Im talking millimeters at a time. If you really want to hear how drastic that little change can be, record another clip, and then compare it to the clip dead center: you’ll see just how much small increments make a difference.
Get a great sound with a single mic FIRST. Do not attempt to throw other mics in immediately, or at all. If it doesn’t sound great with one mic, it’s gonna suck even more with 2 if you actually volume match and listen. Learn how to get a great tone with one mic first, this is an important skill set to learn in my opinion.
And that’s it. Literally that’s it. A decent preamp, a 57, a good amp, a great cab, good playing, and you’re gonna have a phenomenal sound I guarantee it.
also it’s important to understand that the less overdrive you use, the less those mic movements will “matter” so to speak. Distortion is essentially white noise that covers the entire frequency range, the cab is the filter for this pink noise. As you decrease overdrive, you will not get such drastic changes in high end especially the farther away you move the microphone from the center of the speaker. That’s also important to remember.