No Joe Fridays

Many factors contribute to short vacancies and quick turns of empty units.  You have to know your market and present your units well.  Immaculate and with appropriate updates.  Price them well and respond quickly to requests for showing.  Good signage and well chosen web advertising.
Many tenants will begin their search on the web and your ad has to be attractive enough to convince them to take a closer look. If your ad is their first impression of the unit and it doesn't grab them they'll keep looking elsewhere.
Some ads read like Joe Friday wrote them.  Just the facts, Ma'am.  Yes ads must be factual, must not be misleading and must not violate any laws.  But that doesn't mean they have to be boring!  A boring ad is a missed opportunity.  A well written creative ad is a great tool in your arsenal to shorten vacancies.  When I sit down to write an ad first I look at the unit.  I take photos that demonstrate the size of the rooms and then also take close-ups of any details.  An unusual light, cabinet handle or doorknob, any item that updates your unit and makes it less "cookie cutter".  I photograph trees and plants outside the unit and any common amenities like pools, playgrounds, etc.
I sit down with the photos and a list of the unit's features.  I list features of the surrounding area.  Is it close to public transportation, schools, commuter friendly, parks, Starbuck's, farmer's markets.  I then write the ad as if the tenant is already living there. 
"Enjoy your morning coffee sitting on the expansive front porch".
"Soak away the cares of the day in the master whirlpool tub".
"Enjoy spending time with your guests as you whip up a quick bite in the open kitchen".
Picture the tenant in the unit, in the neighborhood, and describe living there.
Once you have the ad written the title is crucial.  On websites such as Craigslist the title is the first thing an applicant notices.  If it doesn't reel her in she won't click on the ad.  Decide what the most salient features of your unit are and make sure they're in the title. 
Sell the sizzle.