Shorter is better than longer.
Short sentences are not always the best sentences, but a shorter sentence is always better than an unnecessarily long sentence. If your sentence is longer than three lines, cut it. If your sentence seems very complicated, or you can’t understand it when you first read it, cut it down. For the most part, try to use short words rather than long words (remember, most short words are more immediate and exciting than long words). Use long words to dress up a sentence that can already be easily understood.