Kevin - I can't believe that you have the ability to write, sing and play but don't have the ear for mixing and mastering. Its all in learning and developing the skills.

Having said that, I second this - I suck at mixing/mastering.

To everyone else - what should we be listening for and are there any rules/guidelines we can learn and use? How do we get our work to sound like the pros (presumably using only 5 minutes a day and for 3 easy payments of $19.95)?!