"Suit the action to the word, and the word to the action."
- William Shakespeare
Invigorate your prose. Use vivid verbs and sparkling nouns. Infuse your instructions with energy. Put passion in your prose.
Write instructions in the command form. Speak directly to the user. Use the form, "You <action> or simply, "<Action>."
Write descriptions in the active voice. Put the action in the verb. Give each sentence an actor and an action. Save the passive voice for just transposing subjects when you need to maintain topical continuity.
Pay attention to rhythm. Read your work out loud. Readers "hear" what they read with their inner ear. Listen to the cadence: the energetic rhythms of your voice.
Vary the length of your sentences. Establish a breathing rhythm. If you put short sentences between longer ones, you give the reader mental room to breathe.
Emphasize important points. If you are introducing a new concept, or an abstract idea, place it at the end of a sentence where it will receive the most stress. Conversely, place simple, concrete and familiar concepts toward the beginning of sentences to give readers a running start.