Writer Lori Mortimer has one simple rule (that's actually followed up with lots of good tips) to improve your writing: use active voice.
Use the active voice. Instead of saying, "The running back was tackled by the linebacker," say, "The linebacker tackled the running back." The passive voice moves the actor (subject) away from the action (verb) and makes it seem like the whole world sits around waiting for something to happen.
One Simple Rule for Improving Your Writing [Blogcritics.org]