Use adverbs sparingly. Adverbs tend to be telling and are a sign of weak or amateurish writing. Verbs are much stronger. For example, compare:
The boy walked slowly down the road.
The boy trudged down the road.
Not only does the second example, which exchanges the adverb for verb, offer a more powerful visual to the reader, but it also injects more tone and emotion into the scene. Much stronger. Adverbs have their place, but do watch for -ly words in your writing and at least consider whether there is a stronger, more vivid way to write the sentence.
Write in active voice versus passive voice as much as possible. With active writing, the subject of the sentence is, as the term suggests, acting upon something. With passive voice, the subject is being acted upon.
For example, compare: The book was handed to Jim. (passive)
versus The librarian handed Jim the book. (active)
Active writing is more powerful and more visual than passive writing. Although passive writing has its place, it should be limited to less than 10% of your piece.