Can I also suggest, that if this is a task that has been on your to do list (and probably because you dont feel skilled enough), enlist the help of someone who needs a task, The small investment would get it done – finally, its really important for your business to grow. If the database doesn’t exist, they can do the manual work of putting it together, set up Mailchimp, templates, design. I am thinking these are not your skill sets and once you’ve sent the first email you have turned the corner. They might even have the ongoing task of the weekly/monthly comms. In my experience easier said than done. It gets put the back burner again.
But with that database, you can then look at other marketing initiatives depending where your audience sits – but programmatic display advertising and social allow for like for like targeting via list uploads.