Keeping a consistent schedule is something we coach our newsletter clients about. Over time, consistency will show up as loyalty - from both sides of the equation. You are demonstrating your loyalty to your readers by creating and meeting expectations. Your readers become more loyal when you do that.
Being repetitive is also important. Sales gurus say it takes 7 tries to get someone’s attention. Of course, I don’t mean that you should do the same thing 7 times. Be creative and try 7 different approaches. Over time, repetition will show up as diligence and tenacity.
The key words to note are 'over time' because neither of these strategies is instant.