We generally keep our best practices here: https://docs.skuid.com/v10.0.0/en/skuid/best-practices/ and https://docs.skuid.com/v10.0.0/en/skuid/best-practices/upgrade-skuid.html
Prior to upgrading, we recommend checking out the “Heads Up” section: https://docs.skuid.com/v10.0.0/en/release-notes.html#heads-up

When it comes to testing best practices, that varies from company to company. We certainly recommend testing as much as possible. Furthermore:
Salesforce does not allow reverting back to prior versions of managed packages. Skuid always recommends installing new versions in a non-business critical sandbox environment to test all mission critical functionality before installing into a production environment. We also recommend that you update out of date themes when you upgrade. Thanks again for helping Skuid become an even better product!