Before touching DNS, write down what already depends on the domain, especially email. The guide to moving a domain without breaking email shows which records to copy first, and the registrar-or-builder guide helps you decide where the domain should live long term.
Then follow the custom domain guide for your builder. Each one covers the plan requirement, the records to add and the checks to run once SSL is issued. If a domain still is not working, use the documented fixes guide rather than repeatedly changing records.
If you send email from your domain through a marketing tool, set up sending authentication before your first campaign. And read the exit plan guide early: knowing what you can export makes any future move far less risky.