The Best Email marketing strategy will be
1. Build a good email list.
To create a good list, you can use pop forms on your site, create campaign on social media with free take away gift etc. You should use Email Verification API in such forms so the list you are building is accurate. This email verification API's will only allow correct emails to be added to your list.
2. Once you have a clean email list, you need to create relevant content for your readers.
3. Now you can create eye catching email template, using service of Email Service Provider for Business. Using their service, you can create attractive looking campaigns using their built in templates or you can even code your own. They also provide A/B testing environment to check your open and click ratio of your campaign.
4. Always keep your audience engaged. You should send atlest one email every month with good quality content.