Hello! Apologies if any of the below is too obvious, but hopefully helps.
Assuming you're signed up to Mailchimp already? If not you'll want to get that up and running, and then create a list of all your email addresses. There are other platforms, of course, but Mailchimp widely regarded as the best - I've used for years and it's fantastic. You need to be *very* careful if adding existing addresses manually, however, and ensure you're GDPR compliant with everything.
For *new* email capture, create a landing page / sign up form - which can either be a landing page through Mailchimp itself, which they recently added functionality for, or your own custom version (example for our mailing list capture here -- https://www.superstring.studio/mailing-list)
A few other bits of advice:
- Incentivise the sign up - let people know what they'll be getting up front (free ebook, discount code etc)
- Don't spam, but keep your communications regular
- Track your open-rates religiously and tweak your approach based on what's working and what's not
- If you have a multiple games/products, be sure to segment your email lists so you're messaging the right people the right information (people will unsub if you're sending them communicatiosn which aren't relevant)
Hope that's somewhat helpful!
Jamin