1.    Change your attitude about essay writing. Stop using filler words. If your goal in writing an essay is to use the assigned number of words, then you will continue to write boring essays. You will never get better, and you will live a writing life of mediocrity. Intend to say something. Make every word count.
2.    Write more than is necessary. If the assignment calls for 2 pages, write 3-4 pages. If the assignment is 500 words, write 800 words.

3.    Edit for economy. Trim the excess. Begin by deleting entire sections or paragraphs, ones that do not add meaning or are not relevant. Eliminate sentences or phrases that contribute little or are redundant. Get rid of unnecessary words. Pretend you are a security guard and all modifiers (adjectives, adverbs, articles, etc.) are potential intruders. Make sure they belong. Finally, eliminate unnecessary words. You'll notice you can say the same using 500 words that you did using 800 words.
4.    Observe how improved your writing becomes. Once you form the habit of trusting your words, you'll notice not having to cut as much. You'll begin saying twice as much in half the time.