The easiest way to cure your writing of passive voice is to print out your draft, go over every single sentence, and ruthlessly omit needless words.
Look at these two sentences:
1) The food was cooked by Dan.
2) Dan cooked.
Most of you would never commit the heinous crime of writing sentence #1. I've simply used an obvious example of passive voice to show how convoluted sentences melt down into direct statements when you edit with an omit needless words mindset.
A side benefit of omitting needless words in sentence #2: You can eliminate the redundant word food, since it is already implied by the word cooked.