Canny makes running beta tests a breeze. Assuming you're building a popular feature request, you already have a list of people who want it.
When the feature is ready for beta testing, just leave a comment on the post. As an admin, your comments get sent out to everyone who voted. This is a highly targeted message. It's also a great way to thank customers who gave feedback by giving them early access.
If the voters list isn't enough, send a wider message to your user base looking for people interested in trying the beta. We send in-app messages via Intercom. Describe what the feature is, explain it's in beta, and include instructions on how to join.
Once you have the beta running, make sure you keep track of who is in the beta. We create tags in Intercom. You can send out additional requests for feedback and see how people are using the new feature. You can also keep them updated with any improvements.
Your main goals of the beta should be to gauge usage and gather feedback. Sometimes, we make a private Canny board specifically for beta testers. They can leave feedback specific to the beta on that board. It keeps things organized.