Start with a mockup!
You can start with black and white. Good to figure out the meat of the design.
Step 1: start with one color
black, white, and another color
An easy way is to take a color from one of the image.
Or you can find complementary colors with https://color.adobe.com/ja/create/color-wheel
Don’t use too many colors! We already have three colors (black, white, and the extra color). The more colors that you have, the more variables/confusion you have.
Find nice colors/gradients: https://mycolor.space/
Step 2: Add variations of one color
Shades & random shades can be useful to use! A little more contrast.
Step 3: Add a complementary color (if you dare)
Places where you really want to grab attention. Try to be consistent with your use of color.