What's the one thing that's completely key to a solid rhythm section, and extremely important in the overall feel of a song? If you guessed the bass guitar, then you're completely right. Recording the bass is an often-confusing topic, mainly because there's so many options. Let's take a look at the easiest way to get a great, solid bass sound on your recording with as little hassle as possible.
You've probably by now heard of recording direct, or using a DI, or "direct injection" box. If your bass has an active pickup system, you can more than likely plug directly into an input on your interface. If your bass has a more common passive pickup, you'll need a DI box. These boxes are a translator of sorts - essentially line transformers that take a low-level line signal of your instrument and make it compatible with the microphone-level signal that your mixer or interface needs.
Recording direct has it's advantages; you get a clean, unadulterated sound that's really easy to manipulate in digital editing, and it responds really well to compression and EQ. You'll get a sound that's very true to the instrument being recorded, and as long as the instrument and the playing quality are both good quality, you'll be set.
Recording With A Microphone
While recording DI is a really good idea for many reasons, you'll find a lot of players and engineers that really prefer a good amplifier sound instead of DI. I recommend the Heil PR40 ($249) or the Shure Beta 52 ($225), but as long as the microphone has a really solid low-end response, you'll be fine. Follow the same rules for micing a good guitar amp: closer to the center of the speakers themselves for more high end, and farther away to the side for more lows. You'll also find that you won't need to use as much compression when you record the amp, because speakers themselves give off natural compression to the signal.
Compressing, EQing, and Mixing
As we've talked about before, compressing serves several purposes, and the bass guitar is a perfect example of why compression is a good idea. The bass guitar is a very dynamic instrument, and there's a lot of techniques that can cause individual notes to stand out above the mix - just look at a good funk bassist! Add a little compression, and you'll find that even the most technically-perfect bass player's sound will even out and become more friendly in the mix. I typically will choose a compression ratio of 3:1, with a short attack and short decay.
EQ is subjective; a lot of engineers, myself included, prefer to let the bass guitar be the only thing really moving (while still not dominating) in the pre-80hz area. The reason for this is simple: you tend to "feel" the low end, and that's what makes you feel as if you really groove to the song... so do you want the element to be static (the kick drum), or dynamic (the bass)? The bass has musicality, whereas the kick drum doesn't.
Enjoy, and good luck! Remember, every situation is different; the tips here are a starting point for your project!