I'm tracking vocals and acoustic guitar in my studio. Apart the fact that I don't play the guitar very well, the recorded performance isn't always very good.
A great recorded performance starts with a great song. If all you play are full chords with no life and no rhythm, no chord progression, no intent behind the song, it will sound bad, no matter how much money and trouble you spend on what follows. Learn music theory basics, learn progressions, practice your scales, spice up your chords with 5th and 7th and 9th and added and augmented chords. Write a song with a purpose.
Second, the performance: if I had Eric Clapton in my studio, said recorded performance would be amazing. So one thing I can do is practice my guitar skills like I practice my drums skills: learn other people's songs, play along, have fun. If you plan on recording yourself, be prepared, know your song; practice a bit before going for it.
The third element in the chain is the instrument. My acoustic guitar isn't a $2000 piece of amazing art work, but it's reasonably easy to play and has a decent sound. Now, mind you, the strings and the tuning of the instrument is a part of the instrument in my book. Change your strings often, have a replacement pair just in case and tune your guitar; there is no excuse for a badly tuned instrument, whatever it is; tuner are cheap and work very well; you would be amazed at the difference in playing on a finely tuned guitar versus picking it up and pressing "record".
The fourth element in the chain is the microphone. I have two large diaphragm condenser mics. One came with my audio interface (Tascam, not very good), the other one (Rode, much better) I bought because I didn't like the recorded sound of my voice with with the Tascam. So I usually track my acoustic guitar with the Tascam because I have the Rode set up with the stand / shockmount combo for vocals. I'll try the Rode on the guitar one of these days. Recording an acoustic guitar isn't just plugging the mic into the interface, randomly pointing the mic in the general direction of the guitar and start recording. Why? Because mic placement is a job in itself in a large studio. That's what recording engineers do: they place microphones (amongst other things, of course). My studio isn't large by any stretch of the imagination, but it doesn't mean that because I have a small home recording studio I can't try to do what the pros do. So I recorded myself playing a succession of full chords, plucked chords and muted riffs at different distances between the mic and the guitar, with the mic pointing at different parts of the guitar. I then compared (A/B is the official cabalistic term here) the different tracks and found the best combo for me. Generally speaking, the mic's "front" (i.e. where the mic pattern captures the most sound) needs to be pointing at the guitar but not at the sound hole; lots of people talk about the 12th fret as a starting point. Distance is also very important: too close and you'll get lots of low frequencies (low end) and get a boomy sound that's usually not very pleasing (proximity effect); too far and the room reflections will play too large of a role in the sound and the guitar will sound too distant. Find that sweet spot and you'll be very surprised at how nice your seemingly crappy acoustic sound now sounds great.
Other elements might enter into the chain: a pre-amplifier for the microphone (mic pre) if the sound level you capture isn't high enough with respect to the other sources; outboard (i.e. not in the DAW) gear such as compressors and EQ, etc. I'm not going into details here because a) I don't have them b) I don't plan to have them c) They're not mandatory to have a great sound; furthermore, mic pres can "color" the sound, i.e. add harmonics that will change the frequency content of the signal to give it warmth or clarity (whatever that means). I like my sound as clean as possible up until I decide (usually in the mix) that I want to change the sound.
Once you capture your great performance with a well placed mic recording a well tuned guitar with a nice set of new strings, you can start looking at the sonic content of your track in your DAW. If it's not good, resist the urgent to add multiple plugins to "fix it in the mix". Go back to the performance. Change the mic placement: that's the easiest EQ you can possible have! When you get a decent sound that you like, start with taking out whatever comes in the way: use a gate to remove background noise. use EQ to cut off unwanted low end which might compete with other instruments (bass, kick drum); carve out of your raw track something which sounds nice and may a bit thin: that's OK because by doing all this subtraction, you have done two things: allow other instruments to occupy the frequency space and reduce the total energy of your track so that adding other tracks doesn't ruin everything. Notice I said carve out and not add in. That's very important. I would only add or boost certain frequencies in very special occasions. As a noob rule set for myself, I even try to never do it. Carve like a sculptor, don't add like a cook.
So there you have it. If you follow this advice like I've followed it, you'll be much happier with your acoustic guitar tracks. Recording them will be easier, faster, and you will have more energy to spend on the other tracks that will make your song sound great.
