Here are some tips about recording electric and acoustic guitars. What I will write here is, of course, very subjective. The contemporary guitar is a very pronounced instrument and various people like various things. Nevertheless, here are some things that work well in general.
You have to start with a nicely sounding guitar. We used to record with a classical nylon-string Alvarez, which has a great, clean, and deep sound that is good for distinct clean solos. For this guitar I would use a Rode NT microphone as it picks up the whole frequency spectrum of the guitar and creates a clean accent and a good sustain. For this particular guitar I avoid using any equipment that colors the sound.
Some time ago I bought a Takamine (a Jasmine). This guitar is very comfortable, but it does not have a nice sound. Compared to the Alvarez my Takamine is "thin" sounding. This is not great in general but I can use this guitar to record strumming accompaniment as it will not interfere with the vocals. Since the Takamine sounds thin, it can be easily distinguished from the vocals. I would set up the Takamine differently from the Alvarez. I would use a Shure SM57 instead of the Rode NT and I would run the SM57 through a vocal tube microphone preamp (a Presonus TubePre). In other words I would look for some coloration when recording the Takamine. The SM57 would miss some of the squeaking of the bronze strings and combined with the tube preamp will make the recording warmer.
For all acoustic guitars my microphone setup is simple. I usually point the microphone towards the place where the guitar neck meets the body (a little off from the hole towards the neck). This is less important for the Rode NT as it has a cardioid pattern and more important for the directional Shure SM57. If I use the Rode NT I would keep it about a foot away from the guitar. If I use the Shure SM57 I would keep it about half-a-foot or less from the guitar.
There are of course a lot of acoustic guitars out there and they all sound different. My main criterion for buying the Takamine was its comfort and not its sound. If I was going for sound and I still wanted a somewhat cheaper guitar I would probably buy an acoustic Fender. Your recording set up could vary depending on the guitar you use, but the important point to remember is that most acoustic guitars are very usable for recording. I think it is more important to pick the guitar which makes your playing enjoyable rather than pick the guitar with the greatest sound.
Recording an electric guitar is more complex than recording an acoustic guitar simply because there are a lot more options. There are a lot of pickups, amplifiers, speaker cabinets, effects, and other gear that you can use. The ultimate recorded sound is very dependent on that gear and not only on the guitar. Thus, it is more important to pick a comfortable guitar than to pick a great sounding guitar. I tried a few Les Paul guitars and even though they generally sound good I find them uncomfortable. I have tried Ibanez and Jackson guitars with similar success. I settled on a cheap Fender Stratocaster with Seymor Duncan Little ‘59 pickups. I chose these as they are one of the few good single-size double-coil pickups on the market, and as they were quieter and softer than other similar pickups. My friend uses a Fender Stratocaster, but with Joe Barden S-Deluxe pickups. I like those better, but I could not find them at the time. These are similarly single-size double coil pickups. I was never happy with the original Fender single-coil pickups for two reasons. First, they picked up too much noise from my first computer monitor. Second, as far as I can tell for some reason the structure and placement of the original Fender pickups is always such that they have problems picking the E string. I re- wired my guitar so that I can switch to using the neck and bridge pickup at the same time and put heavier strings (11s) than the original (9s). So far I have used this guitar for all my recordings.
I used various setups to record my electric guitar but I will mention only our most successful combinations. The best clean guitar that I have even recorded was through a solid-state cheap Fender amp outputted to a bass cabined with a 15” Fender speaker, close miked at half-foot at speaker center with a Shure SM57. The sound is bass heavy with a strong clean accent and sounds very close to an acoustic guitar. I cannot remember exactly what type of a Fender amp that was. If I remember correctly it was the Fender Frontman 25R, which is a 25-watt amp with a 10-inch speaker.
The best pure distortion I got was from the same solid state Fender amplifier taking a headphone out directly into my soundcard. Controlling the noise of this set up was difficult, as the Fender amp is very noisy but luckily the apartment that I was in at the time had a good electrical wire without much of the 50 or 60Hz electrical line noise. Whatever was left of that noise was lost in the distortion as I turned the distortion very close to the maximum. I used this setup once and have not used it since as I can no longer control that noise at my current place. I would like to mike this amplifier, but the problem, besides the noise, is that it is a 25-watt amp, which is very loud for a small apartment.
Most of our other recordings were done through the Line 6 POD 2.0 or the Line 6 PODxt. At this point I prefer the first one, which is the older version. The amp models of the POD 2.0 are easier to get to as there are fewer of them and choosing them is done through a knob. If I am to use the POD 2.0 I would generally use the following amp models: Black Panel, Brit Blues, and Tube Preamp, in this order of selection, with various drive settings, and bypass on the effect knob (most of our production is done post recording). If, of course, you are looking for high gain amps you have other choices, but whenever we look for high gain sound we generally scroll through the POD 2.0 presets and stop at 9C. With the POD 2.0 I have had good luck both recording the out signal direct and miking it through a speaker cabinet.
The PODxt on the other hand offers more amp models which can be combined with various speaker cabinet models for a lot more combinations. Not to mention that you can also purchase additional sets of amp and cabinet models for even more solutions. On top of the fact that there is a lot more to choose from in the PODxt my experience has been that the default amps provided with the PODxt model mostly high gain amps, such as the Line 6 Agro. When recording the PODxt I generally stop at the following amps: Line 6 JTS-45, Line 6 Agro, and Line 6 Clean. Some of the remaining PODxt amp models are ridiculously high gain (Insane, Lunatic, Treadplate), whereas others sound strangely produced (Spinal Puppet). I have not yet purchased any of the other amp packages from Line 6, even though I have been eyeing the Fender one for a while. Also, I would normally use the Fender Blackface Deluxe cabinet. Of course, you can tweak each amp and cabinet combination to various end results. Similarly to the POD 2.0, we would record the PODxt these mostly direct and sometimes miked, preferably through a large speaker cabinet.
The problem with so many choices on the POD and the PODxt has been that our final collection of songs now appears to have very inconsistent sound. That is, as we tend to choose different amps and cabinets for each song, almost each song sounds differently than the rest. While it is good to select the sound of the guitar according to the song idea, too many changes throughout an album could be a problem. We are now of the agreement that when using the PODs one should generally pick one good clean sound and a couple of distorted sounds and then one should try not to deviate from those. A friend of mine recently bought the VOX ToneLab which is essentially the same idea as the PODs, but with the addition of a power amp tube. The sound is definitely nice, even though I had trouble finding a clean guitar sound. The effects are also good. At the time of testing it I paid specific attention to the reverbs as I wanted to use them during the mixing of my songs and I can say they sound very natural. Long story short, my friend has now also stopped on a single amp model and uses that one almost exclusively.
The key to recording electric guitar is consistency. I recently decided to discard much of this setup for a single amplifier setup that I can mike for most of my recording needs. Even though I have not yet done so, it is worth mentioning that I did try various amplifiers and the one that I found cheap enough and good enough for the purpose was the Fender Blues Junior, which is a 15-watt amp with three preamp tubes and two output tubes and with a 12" speaker. I like the fact that it is 15-watt as opposed to my solid state 22-watt – if I could find a smaller wattage good amp I would use it. I very much like both the clean and distorted sound coming out of the amp due to the tubes and the nice speaker. The Fender reverb is always a plus.
Is it worth to go to a single amplifier when there are all these other options available? The Fender Blues Junior is priced between $500 and $600 and if I was to start anew that is as much as all of the rest of the equipment mentioned here. You can get the POD 2.0 for about $300, and the PODxt anywhere between $300 and $600. The price of the VOX ToneLab amp modeler is about the same as the POD. With the PODs you definitely get a lot more – more amps and cabinets, more effects such as good reverbs, which incidentally you can use in your post production, and others. A single nice amplifier on the other hand gives you quality of sound which cannot be replicated. Knowing what I know now I would probably choose the single amp solution rather than the amp modelers, but that is ultimately a choice that everyone should make on their own.