In need of a haircut, I recently stopped into an unfamiliar barbershop to get a trim.  After the usual 20 minutes of snipping and masculine small talk, the barber rang up my bill, charging me $13 for the cut.  Then things got interesting.

"If you'd like, you can pay $30 now and get your next three cuts for free."

I did the math in my head.  That's really not a bad deal, of course.  Instead of paying $13 per cut, I'd only be paying $7.50 per cut.  I glanced in the mirror, realized that the barber had actually done a pretty good job, and said, "Sure, why not?"  He took my $30 and gave me three vouchers for future haircuts.

I walked out feeling like I got a pretty good deal.  Then I realized the power of the situation -- the barber had just taken in $17 more than he normally would on that haircut.  Sure, I might end up using those vouchers, but even in the worst case scenario -- I use all of them -- he's still filling his chair if only at $7.50 a pop instead of $13 and he's got all of that cash up front instead of spread out down the road.

It's called a continuity sale, and variations of it abound all over the place.  If you've ever seen or used a business punchcard -- you know, those "buy five pizzas, get one free" deals -- you've seen continuity sales at work.

Here's the thing: they work in virtually any service business to increase the number of sales you'll make.  Take that barbershop incident, for example.  He essentially turned one sale at $13 into four sales: one for $30 and three more at $0 a pop.  Or that pizza place -- if you bring in a filled card, they're happy to give you that pizza because you've bought four pizzas at full price -- five sales at $10, $10, $10, $10 and $0.

How can you make this work for you?  Here are four quick ideas that go beyond the punch card.

Sell packages of vouchers.  This is essentially what the barber was doing.  He was selling vouchers for future haircuts at half price.  This has the advantage of getting you the cash up front, of course, but can reduce your total income over time if the person has the wherewithal to use all the vouchers.  You can do this with anything: pizzas, dinner specials, oil changes, website maintenance -- the list is endless.

Turn receipts into coupons.  If a person shows a valid receipt from your store from within the last month, they get a small amount off of their purchase.  This encourages frequent repeat customers -- and if you have a repeat customer, they're worth the small amount you lose in income for each receipt shown.

Turn proofs of purchase into coupons.  If you're the exclusive seller of a particular product in your town, you can literally turn pieces of the packaging of that product into coupons.  For example, if you're the only seller of a particularly good type of oil filter, offer $2 off that oil filter if someone brings in the box lid from one of those filters.  Again, this encourages continuous sales of the same item.

Offer a discounted scheduled maintenance package.  Many stores offer maintenance packages on their items with limited success.  Instead of just offering one maintenance service, offer several together as a package.  For example, if you sell air conditioners, sell a package of annual maintenance for the next 10 years for a set price that's much more than you'd sell a single maintenance for, but far less than 10 of those packages.