Whenever I am creating an analytical visual/dashboard, I start/finish the visual with absolutely no colors. This was something I picked up during one of Cole Nussbaumer’s podcasts—I highly recommend for anyone looking to learn/improve your data visuals skills. Now after finishing the visual, you can then look at the entirety of the visual to determine what values/items need to stand out. But first consider, can you use shading to help it stand out? If colors are appropriate, do they relate to what is being presented?
I came across this website by canva.com and have used it often when I needed eye-appealing color combinations. Bookmark it, I think it could be very handy as you build out your visuals.