I like to leave a couple of seconds of silence at the beginning of the wav file in Audacity. Also when you choose your mp3 compression rate pick the highest rate or at least 196 and it'll sound better.

Your next question will be where to put it so you can share it. Soundclick or Soundcloud are both free to upload your song to share with the world. Once you have it there put a link to it on the users showcase forum or the off topic forum and if you'd like feedback on something specific like the mix just ask for it.