1. Join the Release Readiness Trailblazers Chatter Group.
https://trailblazers.salesforce.com/_ui/core/chatter/groups/GroupProfilePage?g=0F9300000001oku

2. Create a Pre-Release org to check the new features.

3. Check the Salesforce Release Notes which are published few months ago the Release.

4. Give special attention to product changes and Critical Updates from the Release Notes.

5. Schedule a meeting with the Stake Holders and Business Owners and demo the Out of the Box features that helps their Agents/Users in their day-to-day activities.

Check the Sandbox rollout schedule and do a regression testing in the Sandbox well in advance.

After the production schedule, do a thorough regression testing.

Trailhead Resources
1. https://trailhead.salesforce.com/en/content/learn/modules/sf_releases
2. https://trailhead.salesforce.com/content/learn/modules/advanced-salesforce-release-readiness-strategies