Drive behavioral change with habits
People are creatures of habit. They fall into routines, do similar tasks from day-to-day and live in a bubble of their own creation. Their habits are cyclical, there is a holiday season, spring season, back-to-school and so on. People are predictable in their patterns.
When it comes to advertising or marketing then, you need to wonder: Are you trying to take advantage of a habit? Are you trying to break a habit? Or are you trying to increase or decrease a habit?
Given that people are predisposed to order their lives with routine, they need a good reason to break it. You may be the best in the business, your company might offer the best in the market, but the customer still needs convincing to actually make the change.
Know if you are taking advantage of existing behavior or changing behavior is step one. Oreo's "got milk?" campaign is a direct example of taking advantage of existing behavior like eating cookies or peanut butter sandwiches and asking if people remembered to buy milk with it. It took advantage of people who already enjoy certain products and reminded them to increase their purchases.
And breaking or changing habits? It's harder than people think. There are plenty of examples of human behavior at odds, people knowing what the correct or expected behavior is but not following. For example, gym memberships go unused, cigarettes are still being sold and doctors are still avoided. So what can advertisers do?
Think about what drives the behavior of interest. People didn't buy more milk after learning in multiple campaigns that it was healthy for them. People bought more milk because of an aversion to running out.
If you want any additional reading, you can learn more about what drives behavior with Drive by Daniel H. Pink.