The best strategy is to treat your email list like the valuable asset that it is. When you are planning out your content, think of ways that you can add value and do so in a consistent manner. This can include tips and advice, special promotions or discounts, or even simply showcasing some of your latest products or services. The key is to keep it fresh and relevant – but also make sure that you don’t go overboard with too much email every day. 3-4 emails per week will be sufficient for most people.