How Do You Record Acoustic Guitar ?

I prefer the mic in the room and in front of the guitar about 12" or so. The pickups on acoustics are generally not very realistic so a good condenser mic, properly placed wins the day.  You need to experiment with placement to see what works best. 12" to 18" over the 12th fret is a good starting point for a single mic. Dual mics...also mic the body near the sound hole but not in too close.
 
As far as EQ and compression, only use what you need. Nothing more, and nothing "just because"....
 
FX.... nope. I will record it twice and pan it for a doubled thicker sound.
 
That's "in a nut shell" on how I record acoustic.

Under saddle as last resort.

Two small diagram condensers is best. One for strings fingers and treble.
One for bass, body sound.

A well placed large diaphragm can work too. No phase problems that way.

Bule
Gonna have to try that with the condensor Not sure I can double track or do you guys mean clone track. This is a fingerpicking piece and I can get close but not sure how exact on a double track.

You want a little difference between the two tracks. That's where the magic happens. You don't want it completely different, but just enough to make it sound big.

Good luck with it!

"I spent a day positioning mics and settled on a single 57 at a 45 degree angle toward the sound hole from the bridge at about 8 in. "
 
A 57 is not the right microphone for a clean guitar sound.  Micing an amp, sure, but not for acoustic.  Even a cheap MXL SDC would do a better job.   Use two, record stereo.

bayoubill
A 57 is not the right microphone for a clean guitar sound.  Micing an amp, sure, but not for acoustic
Thanks for the input!
I also have a bluebird cardioid capacitor microphone. I haven't used it on my acoustic guitars yet.

The Bluebird would be a much better choice.

I've heard great things about the Mojave mics, especially the tube mics. I use an older sE tube condenser and also a RODE NT1-A, and have had good luck with both.

I get pretty decent results using my "cheap" MXL 63m, recording my Larrivee.  The Larrivee sounds fantastic, so all I need to do is capture what I hear, cleanly.  I would start with a single condenser positioned as suggested above.  Small movements with the mic can make a big difference in tone.  Closer for more presence, further for more room.  Closer to the sound hole gives more bass or boominess.  Somewhere around the 12th fret is a good starting point, about 10-12" away.  Master one mic before moving on to 2, my opinion. 
 
You can check out the tones I get at my Sound Cloud site. 

Don't clone the track. Record it 2 different times in 2 tracks.....pan one right the other left. I tend to go 100% left and right respectively. Generally this is on the STRUMMED acoustic only. I try to get it as close to the same as I can knowing that there is ALWAYS going to be a difference and the result is a tight performance with a W I D E sound. All other instruments in the mix are closer to center and the mix sounds full as a result. The acoustics are generally mixed -12db or so... so they are not up in your face. They simply provide the ambiance needed. I do tend to scoop the mids out a bit depending on how it sounds to get it cleaner without the boxiness that acoustics like to produce.
 
Most all of my music uses this if there's an acoustic guitar in it such as here>>>>  http://soundclick.com/share.cfm?id=12024980
 
The mic you buy will depend mainly on your budget and what you can afford.  I have a Rode NT-2A condenser that I use for just about everything and a dynamic SM-58 I use on cabinets.  For the low budget, a company called Gauge Microphones USA has very inexpensive but good mics. (Mail order/internet only)
 
I would only use a built in pickup on stage to get the volume up and into the PA..... not so much in the studio. I have a guitar with a pizeo pickup in it and it works fine for stage and live performance where the sound quality isn't required to be perfect.

https://www.youtube.com/watch?v=wiZFtN1xm-U

Yes, lots of information. However, too long, didn't read. The M/S vid I posted, "I use!" Less filling, and tastes great :-) I use a Neumann U87AI as my figure 8 mic, and a Mojave Audio MA100 as the mid, through some nice pre-amps, and I am very happy with the results.