Simulate production builds with your GD&T to determine the chance of failure, and the causes for failure. Hone in on these contributors to variation to tweak your GD&T until it provides maximum quality. Simultaneously find non-critical areas to increase tolerances (loosen them) in order to reduce manufacturing costs.
Validate your design using the Digital Twin to reduce prototypes and physical testing. Find potential issues, and make sure your design will build, assemble, and function every time. Test solutions to problems found in production before rolling them out instead of costly trial and error.
Use GD&T and model callouts if you have them, or utilize Linear Dimensions and Tolerances by putting + and - specifications on your product. Start with general callouts, then hone in on critical features to tighten, and non-critical to loosen. Combine both tolerancing methods to replicate part and assembly tolerances, as well as processes and additional influences like tooling.