Songs usually sound best if the drums and bass are centred, and the guitars are panned left and right. The vocals are usually best centered as well.

One thing you can do is record the drums on track 1. Then do the bass on track 2. Then bounce both those tracks down to track 4.
Start again on track one and do guitar for the left track, then use track 2 for the right guitar. Then use channel 3 for vocals.
If you need to do harmonies, you can record them at the same time as you do the left and right guitar tracks or plan things out ahead of time and use the remaining tracks to build up a 4 part harmony.
As far as levels are concerned, the hotter the better. Get the levels as high as you can without distortion.
Plus if you do a lot of bouncing down, the less noise the better, so get rid of any amp hiss or room sounds.