There are basically 2 schools of thought on how to record acoustic guitar and vocals at the same time and I assume that is what you are really wanting to know about because almost anyone can record them separately. One technique, which I prefer, is a 3 mic system using 2 small diaphram mics on the guitar as a spaced pair (panned hard right and left in stereo) and then a large diaphram mic down the middle for the vocal. I will usually aim one small diaphram mic at the bridge of the guitar and then the other one at about the 12th fret. Obviously, this has the potential to create phase problems with the vocal mic in the middle, but it can also sound really cool and give you a natural 3D type sound and a sense of the acoustic space (and this only works in a good sounding room). It's also possible to put the small diaphram mics in an X-Y pattern in the middle but, at least for me, that has created more phase problems than the spaced pair because the small diaphram mics are too close to the single large diaphram mic. I normally use 2 Neumann KM74's for the small diaphram mics and a U77 for the vocal. If bleed and phase problems start to be excessive, a good trick is to use a large diaphram dynamic, like an EV RE-20 on the vocal in the middle because it won't pick up as much of the guitar sound as a condenser would. You also have to be careful in balancing the 3 mics to make sure the left and right channels are about at equal volume. IF YOUR GUITAR PLAYER SINGER LIKES TO MOVE AROUND A LOT WHEN THEY PLAY, the 3 mic system may not work very well because mic position is critical.
The other school of thought uses 2 mics. Typcially, one small diaphram mic at about the 12th fret and then 1 vocal mic. You would normally mix this in mono (unless you are into extreme stereo with the vocal on one speaker and the guitar on the other). This technique minimizes phase problems and bleed from one mic to the other but will not give you the cool 3d stereo that 3 mics can give. But this technique may be better in a bad sounding room. I would try both and see which one you like better, there is no right or wrong answer here. I would put the same reverb on all 3 mics because it can sound strange with one reverb on the guitar and a really different one on the vocal, but again, whatever sounds best is what you should use.