If a track has a blank section (where no part is being played) and there is even a tiny bit of noise; cut it.
This especially tru at the beginning and end.

I can't tell you how many mixes have had to have the end reworked because there was so much noise as the last notes died out.

http://musicmastering.org I suggest maybe looking at the mixing and premastering pages.

I do not work here, but the benefits are still awesome
Make your sound your own!