Behavior change is simple, but that does not mean it is easy!
As a designer or business leader, your aim should be to help your customers, employees, or even yourself make better decisions.
Forget the easy tricks and gimmicks, they seldom work in the long run, and frankly, they aren't ethical or helping anyone make better decisions, as you will have to eventually deal with the spillover effects of your tricks.
My advice:
>Follow the principles >Use the evidence >Work systemically >Look at both the individual and the system >Be contextual >Test >Iterate >Be Ethical >Above all, strive to help others