Stay in touch.
Keep it simple.
How should I promote?
Your email should get their attention. This can be done with a big sales event or some interesting piece of information about your business that will be a benefit to your customer. The more excited your customer is to hear about what you have done for them, the more they will pay attention to your next email.
Anytime you can use a graphic to illustrate an event, the more likely your customer will pay attention to your email.
Be careful not to “spam” your customers with too many emails. What's important to you, may not be important to them. Before you know it, they may just hit the delete key every time they see your email.