Visual-design principles can be applied consistently throughout the process of creating a polished UX map. Start by choosing a tool, then create a visual system, establish the basic layout, and finally add content and make adjustments.
Members of a design team will often argue for different solutions to a UI problem. That's when to say "show me the data" to resolve the debate by empirical insights, rather than who argues the best.
UI elements that are close together are perceived as belonging together, whereas users think that things that are apart play different roles in the interaction.
What's most useful in building a DesignOps program depends on the level of maturity in the specific organization. In the beginning, focus on pain points. Later, focus on building scale.