Every app, website, project is different. Everything has its own needs, requirements. Every design should represent the project's personality. There should be no two identical designs. Feel free to poke around in the components, shake things up for your needs.
Color is less and less present in our everyday life. Be creative with colors. Use different accent colors. Try different colors before choosing one. Try to incorporate it more in to your design without sacrificing accessibility and aesthetics.
Desktop, laptop, mobile, tablet, TV. Many screen sizes, many ways to control, many things to worry about. The design should be fully respionsive. It should look aesthetic on all sizes. The transition should be easy. Using the mobile app for exaple for the same project should be natural for the user. Navigation, design and overall feel should not change.
Accessibility is important. The design should be informative but easy to understand. Don't use too much text. Don't overclutter things. Related information should be next to each other.