We spend a lot of time and money trying to attract the attention of customers, prospects, and other stakeholders. We develop sophisticated email campaigns. Spend thousands of hours on social media. We invest in every form of advertising, from bus ads to skywriting to 30 expensive seconds in the Super Bowl.

While some of these efforts are effective, we often agree with the iconic retail magnate John Wanamaker, who famously said, "Half my advertising is wasted, I just don't know which half."

That's why it's fabulous to find a simple, persuasive method that works. The technique? The humble Post-it note.

I recently rediscovered a study by Randy Garner in the Journal of Consumer Psychology that demonstrated the power of the Post-it note.

Garner, a professor at Sam Houston State University, decided to find out whether a Post-it might have the power to make a written request more compelling.

To do so, he conducted this experiment: He mailed a group of people a request to complete a survey. Every package contained a cover letter and the printed survey, but the mailings had three variations: one-third included a handwritten Post-it note requesting that the survey be completed, one-third a similar message hand-written on the cover letter, and the rest only the typed cover letter and survey.

What Garner learned is that the Post-it note worked best: 78% of people receiving the first package responded, as opposed to 48% to the handwritten note on the cover letter and 36% to just the cover letter.

Why? Garner believes that "a handwritten sticky note conveys a more personal request, one that urges the recipient of the request to reciprocate this personal touch by agreeing to the request."

In fact, not only were people more likely to respond to the request because of the Post-it note, the quality of their response was better as well: People in the Post-it group "returned their surveys more promptly and gave more effortful and attentive answers to the questions."

This technique obviously can't be applied to every situation--you probably don't want to attach a handwritten sticky note to, say, 40,000 newsletters. But have you thought about how you can make communication more personal? Are the answers to some of your communication challenges simple and low-tech, rather than complex and expensive?