Here's a little evil tip: Save your audio sweetening for the end. Why? Well, have you ever had a client who keeps monkeying with the project making irrelevant changes and basically just toying with the edits for no real rhyme or reason?
What I do is save the audio sweetening and music levels until the very end. After seeing so many versions with poor audio, then suddenly seeing a version with music levels up, audio panned correctly (usually just centered if someone decides it's a good idea to have offset audio channel levels when audio was recorded to "save" the peaks...grrr) the client will think some miracle just happened and often they'll love the version. Evil yes, but so is making dozens of meaningless tweaks over a week.