Avoid long sentences.

Avoid long, involved sentences. It may have worked for the apostle Paul, but your writing is not quite on that level. Fifteen words or less is a good target, though definitely not a hard, fast rule. The point is not that you should count the words in your sentences, but that you should be economical in using them, clear and to the point. You don't want your readers wandering in a maze of confusing clauses.