Besides being able to play the instruments to a high standard with polished technique, good quality gear really helps. A nice guitar with good pickups, a good audio/digital convertor is very improtant for capturing the sound is a must. Preamps compressors etc all depend on what you are recording. I use a UAD-1 card for post recording insert VST effects and compression, it's great and means that I can make non destructive changes to reverb levels etc at any stage in the mix. Really the most basic part of the chain is a good quality soundcard. As Kevin mentioned, MP3 loses clarity when converted down from wav so keep the bitrate as high as possible for mixdown. Also, you need to make sure you are recording wav - at least 24bit 44Khz (32bit float is better if your system can handle it and IF you are pushing towards levels that could otherwise clip). Mastering makes a massive difference to a final recording, I use a combination of a limiter and the magneto vst plug-in to add warmth (makes such a big difference). I add this to the final mixdown stero wav then convert to 320kpbs MP3. You can tweak the overall EQ at this stage too but that is way beyond my level. Getting your own sound has a lot to do with experimentation and luck!