While not the most pressing need in the initial stages of designing a product, it’s important to think about the look of your program. The sooner you pick a template and palettes, the better your workflow will be. It’ll also be important for everyone to be on the same page in your team about the look of the program, especially if you are all working separately for a while. Here are a few tips and tools to use
Material Design by Google is a great tool for this: https://material.io/resources/color/#!/?view.left=0&view.right=0&primary.color=F44336
You can also use http://colormind.io/bootstrap/ .
You can cycle through the choice and find a color that works for you and your stakeholders.
Three great principles to follow are:
Make sure to check out mateirla.io for more guidelines on colors and design.
If your creating something for Macs or iPhones make sure to check out : https://developer.apple.com/design/human-interface-guidelines/ios/visual-design/color/
As soon as you feel a page/screen has too much going on, think about how a different page/screen could help it do its job.