In addition to choosing strong verbs, nouns, adjectives, and adverbs, you must be alert to strong sentence structure. Keep in mind that the active voice ( Ernie built the house) is almost always stronger than passive voice (The house was built by Ernie). Search your prose for passive voice and root it out! Your writing will be more vivid for it.
Pacing
Keep it moving.
Hook 'em, keep 'em in suspense, and don't let them go until the climax.
Pacing means not letting your story get bogged down in long expositions, flashbacks, dream sequences, infodumps, AWAKs, and so on.
Definitions
Pacing means not getting lost in digressions or scenes that aren't going anywhere. Pacing means always asking yourself, as the author, "What am I trying to convey in this scene? Does it need to be here, or can I cut it and move things along more quickly?"
Someone once said that before the first chapter is over, at least one character should be hit over the head with a tire iron. By which he meant (I'm pretty sure it was a he, with a metaphor like that) you shouldn't waste time getting the story moving. Make sure there's enough drama, early and often, to keep the reader interested.