It's easiest to setup your stuff (and easiest to give advice) if we know what kind of music you are going to make. Obviously the equipment needed for electronica is different than indie, but even within 1 genre - if you are just going to produce acoustic, singer/songwriter songs than the sound of the acoustic is paramount and you would need to pay attention to it. If the acoustic guitar is just always gonna be rhythm guitar in a dense mix, then it's not as important.
Do you have an audio interface? This is beyond necessary..
As for mics, small diaphragm condensers (SDC's) work very well with acoustics, especially in a stereo pair. Large diaphragm condensers are often used. Dynamic mics dont have a large enough frequency response to pick up all the tonalities of an acoustic. I often read that ribbon mics give a very natural sound, but they are typically very expensive...
By far the biggest impact on the sound of your ac. guitar (apart from the performance) will be the room. It will be necessary to treat the room in whatever way you can. There's tonnes of stuff on SoS about it. The idea is not necessary to 'kill' the reverb in your room, but to even it out and generally make the room sound nice. The biggest problem is usually bass build up (especially in small rooms like bedrooms) and bass traps on the corners are usually necessary.
With setting up mics for the guit, best is to experiment. Having the mic about a foot away from the guitar will give a natural sound. This will also pick up a lot of the sound of the room and if the room doesnt sound good...
You can reduce the sound of the room by moving the mic closer to the guitar, however, the closer you get, the more you get the 'proximity' effect whereby the relative level of low tones is increased - the guitar becomes to sound more boomy.
Also experiment with adjusting the lateral position of the mic. I tend to mic my guitars with the mic pointed more towards the 12th fret and not the sound hole - the sound hole can be too boomy, and the closer you get to the bridge the more harsh sounding it gets.
With electric guitar, I find the best way is almost always to mic the amp - a dynamic mic like an sm57 works well. If you do DI the electric then there are lots of amp simulators out there which are prett good. Stuff like Waves' GTR.
It all depends on how much you want to spend. But if you do have something to spend, I would do these things first:
1. Treat the room. Go on to the auralex website and go to support -> room analysis. You can upload a diagram of your room and get a free analysis of what needs to be done (and of course, all the products of theirs you should buy). If you have time I would build your own bass traps and acoustics with rockwool/plywood. It is A LOT (more than ten times I'd say) cheaper. Here are some great instructions:
http://www.ethanwiner.com/basstrap.html2. Get an audio interface (if you dont have one). The most important thing here is how many inputs and outputs do you want (If you are multitracking, you might say, well just 1 - but I would go for 2 to be safe. What happens when you get another mic and want to put 2 mics on your guitar? Or if you want to play guitar and sing at the same time?. Audio interfaces are updated as much as computers, which means they go for very cheap 2nd hand. I got a 12 input/output Layla 24 from ebay for £80. It's a high-end interface that went for £500 new.
3. Get a condenser mic (if you dont have one already). Good budget ones would include the rode nt1-a, rode m3, audio-technica at2002 or something. Again the 2nd hand market can be useful, I often see the following high-end mics go for much cheaper on ebay:
Neumann tlm103
Shure sm81
AKG 414
