At the core of permission marketing is the efficiency of earning, maintaining and leveraging attention.
If you don't have to begin anew each time, you can cut the effort and spending you're putting into reaching strangers. And if the consumer can trust that you won't waste her time, she can spend more time on productive work and less time sorting offers to see what's worth looking at.
The method for accomplishing this: make promises and keep them. Make an offer and then follow through. Don't waste my time.
The advanced method: intentionally design your communications to create a habit of attention. Habits are hard to form and even harder to break, and when properly constructed, they can benefit both sides.