Some of you might recognize our amazing (and cute) singer. Aside from playing with our band, she also does solo covers and ultimately we'd like her to be a successful solo artist.

This is just pointless preamble. My real question is this: what is the the best practice for recording her voice and guitar through just one microphone? Her other videos unfortunately used an iPhone, but starting with the one linked here, we've found her a (what I believe to be) decent condenser microphone, specifically, the Zoom Q3 which has dual X/Y configured condenser mics. (whatever the heck that means). Since I do all the mixing, I am also the one to have mixed this. I compressed it slightly to eliminate spikes (low threshold, low ratio but super fast) and I equalized to make her voice sparkle (cut the lows and boosted highs. played around a bit with mids to eliminate the bassiness of her guitar. I also added quite a lot of reverb, giving it a fairly small response time, about 30% volume and set it to 'bright' (however that is quantified). I do my mixing in Garageband (aka, I use a mac). Other questions I have include where to put the mic (distance and orientation to her and the guitar) and if there is a better way of recording guitar and voice which will give me more control over each.

Thanks in advance for your help! I'm self-taught and everything I know about mixing comes pretty much directly from reading other discussions on here You can download/listen to it at a higher quality here: http://snd.sc/Imq8fJ

Or just watch it on YouTube:

You did just fine with the equipment you have. - The only thing I would do is set up a recording session and experiment with mic positions, dare I Say it the one in the video is probably going to be hard to beat.
You want to avoid recording from the bout side of the guitar, unless you were recording with two mics.

If I were you I'd just work on the mic distance, a little further away I'd suggest, this will lower the Bass, and perhaps slightly angled down, but this may not look good visually, generally videos of artists are looking up to them.
Why not record the video with you iPhone and ZoomQ3 - you can edit out the audio with many video software, matching the sound wav to sync them.

Have you tried recording Monica in open spaces, say a nice park, or just a decent setting, you may need to put a windshield over the mics if there is wind, or just pick a nice day

Alright, thank you! I'm glad I did something right for once (I always think I did it right, but I never know for sure). We will indeed play around with the distance, and keeping it further from the guitar makes sense; I realized that when we were recording one guitar with multiple mics: the bass was always overpowering up close. Can't believe I didn't think of that this time. Right now we actually were recording audio with the Zoom and video with the iPhone, but due to how ridiculously thin the iPhone is, there is no good way of angling it (though yesterday I did come up with this awesome mount using a mop and 2 rubber bands! http://cl.ly/Fe8k )

Camera-wise, we should soon have access to a decent Nikon tha'll be able to shoot widescreen (one of my current gripes with her set up is the 4:3 ratio) and at at least 720p, which generally makes my eyes happier. Angling up to the singer is a good idea, I didn't think of that, but angling is really important, on par with body language. Silly me.

As for recording in open-spaces, I've never been with her when she does her covers, but she says that it takes her multiple takes, so I don't know how long we'll be able to have peace and quiet in a park. Also, since we're all Vancouver-based, the weather here tends to ruin our plans ("if in doubt, assume it'll rain" is our adage). And as far as wind-breaks go, her mic came with its own cover, so thats a non-issue. 

Next time she records a cover I will remind her of the changes to be made and will show you guys what happens with it. Thanks for your help Denis

You could also try things like a "green screen", some members here have done some interesting music videos using a green screen..
YouTube have some great tutorials on how to shoot green screen videos - it's a chance to show off your creativeness and imagination, it can be fun too, infact that's exactly what you should do "Have Fun"!