Three is a powerful number that satisfies our deepest needs for symmetry. Three gods ruled the earth—Zeus, the god of heaven; Poseidon, the god of the sea; and Pluto, the god of the underworld. People worshipped the moon goddess as a triad, representing three phases of the moon. There were three Fates, three Furies, three Graces, three Harpies, three primary colors. Three times three was also a mystical number, hence the nine muses.
A few obvious threes from popular culture:
Three wishes. Three bears. Three little pigs. The Three Stooges. Three outs. Best two out of three. Three Faces of Eve. Three Days of the Condor. The Three Musketeers. Third time lucky. Love triangle. (The triangle itself is a divine symbol signifying the power of three.) Three is also a visually pleasing arrangement. And the number three signifies harmony.
So, to make your stories more powerful, harness the power of three.
1. When describing a character or scene, mention three attributes. Also, if a particular attribute needs to be fixed in the reader’s mind, mention it three times (and only three times) during the course of the book, and it will stick.
2. When devising a plot, follow the storyline of The Three Bears. The first time the hero tries to reach her goal, she fails but learns the risks. The second time she tries, she confirms that she’s doing things wrong, but she learns from her mistakes. The third time she tries, she gets it right. 
3. Look for patterns in your story. If your character has given his love flowers and perhaps made love to her in a flower garden, mention flowers once more to solidify the pattern.
I could give you more ways to make your stories more powerful, but since I’ve given you three suggestions, that should be enough. And if it isn’t, you can find more uses for this powerful tool here: The Most Powerful Tool at a Writer’s Command
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Pat Bertram is the author of the suspense novels Light Bringer, More Deaths Than One, A Spark of Heavenly Fire, and Daughter Am I. Bertram is also the author of Grief: The Great Yearning, “an exquisite book, wrenching to read, and at the same time full of profound truths.” Connect with Pat on Google+
Bertram's Blog 
April 17, 2013 at 4:29 pm
Great advice.
It is significant to play on human psychology that many would argue is innate. It will improve prose dramatically.
http://stephen-leslie-france.blogspot.com/2013/04/rage-against-current.html
April 17, 2013 at 5:05 pm
I see what you mean, but I also like the number 5. It has a lot of significance as well, especially if you read “The Age of Misrule” books by Mark Chadbourn.
April 17, 2013 at 5:10 pm
Reblogged this on DJWritingOutLoud.
April 17, 2013 at 8:12 pm
In Japanese theatre 3 signifies drama or conflict. It is a power number. Traditional Japanese plays have their actors in lots of 3. There are plays with 3 actors. Plays with six actors. Plays with 9 actors and so on. What’s more, this arrangement works.
An argument between two people might never be resolved unless there is a supposedly neutral third party. I was in a play at college that used this principal. It was set in hell. In this play, however, the third party had her own agenda that had nothing to do with what the other two were on about. This agenda, however, could not be successfully addressed by either side to end the conflict. Hell really is other people.
Also, if you want your hero stabbed in the back physically or mentally a third person comes in handy. The hero is betrayed rather than getting his or her chance to tangle with the true enemy. Maybe they get their chance later on or it is up to a son or a daughter to carry on.
In my novel Ghost Dance you have your three in a boy becoming a werewolf, a vampire, and a vampire hunter wishing to save the boy from a terrible fate.
In my novel Desk Job the three comprise of a dead Japanese woman, her killer, and the psychic delving into why it happened.
In the writing I’m working on at the moment, Cold Water Conscience, I have a man haunted by the past, a woman doing the present haunting (no she’s not dead) and the man’s sister who only wishes to help him.
Rami is correct about the number 5. It is also considered a power number.
April 19, 2013 at 12:30 pm
An interesting idea, and I think a good suggestion.