Just read as much as you can on these boards, in books or wherever else you can get info.
Take a studio recording class at your local college.
You will be better off after 2 years of Recording classes for $100 per semester than 4 years of trying to figure things out by yourself.
I started out with the same problems.
Thought I could turn EQ's and volumes up in any direction to what made the tone sound as god like as possible just like I would on a guitar amp.
Learning Gain staging helps too.
Eventually understanding audio for recording will even help you understand your amps better and help you define your sound.
Most metal guys want to turn the Lows all the way up so its heavy, then turn the highs all the way up so its bright and then scoop the mids down most of the way so it feels super chunky. Of course the gain goes all the way up too because you think that it gives you the killer distortion.
All it usually accomplishes is lack of clarity, lack of headroom, but at least you sound good when its just you......
In a recording, a guitar might sound like crap solo'd but sound amazing in the mix.
Same reason people say to ditch the BBE....
Don't get me wrong, I like BBE, I love the Tube Driven Bellari Sonic Exciter More, but in the end, your bassist should be picking up the low end.
You should be able to work with your favorite amp settings.....
You just have to know where the limits are to too much highs, Lows, or Presense, or lack of mids...
For Rythm I recommend backing off of the gain to the point where its just crunchy enough for you, can still get good harmonics etc. Using a good tube screamer helps also....
For Leads you want the gain saturated enough for your tone and playing to come out.
You got the room figured out.....
Sometimes you can even throw a heavy blanket over your cab and mic stand.
Other users suggested pointing the mic strait into the cone of the speaker.
Thats a good starting point but dont make the mistake of just ending there cuz you can end up with super fizzle.
Start there and do like other users said with headphones on and move the mic around between the cone and outside edge of the speaker.
You might even face the outside edge and then point in diaginally to the center cone to get the right sound.
Make sure your amps not too quiet either.
Good Luck.