engine - 5:03 pm on May 29, 2012 (gmt 0)

You may already have done all this.

Consider looking at a budget, instead of every click cost.

Expect to get clicks that don't convert. It's always going to be like that whatever the form of promotion and marketing.

Look at the efficiency of the programs.
Try dayparting so that you're only using a budget and competing when it's best.

Invest more time in keyword research to make sure you've got every keyphrase, no matter how small the numbers.

Test ad efficiency by running different ads. Ditch the ones that don't perform.

HTH