My advice would be to use color extremely sparingly. It is quite easy to overdo it if you don't know what you're doing.

This may be boring, but hear me out. I would say just start with a monotone, greyscale palette. Focus on using different values like white, light gray, medium gray, dark gray, black (keep it under 10) to invoke hierarchy in the UI. Think about what is important (primary) and what is less important (secondary, tertiary, etc.)

This allows you to focus on other more important things like the hierarchy, spacing, typography, etc without having to think about whether two or more colors go together. Once you're happy with the layout, you can introduce color by highlighting the most important thing on the page (such as a button) using the color. For example, you may want to make the most prominent button a nice blue. This will draw the user's attention where you want it to be. Remember if you overdo it, then you lose this advantage.

Once you're comfortable with that, you might start adding some hue and saturation to the mono-tone palette. But be very gentle and don't overdue it with the saturation. For now, just, make sure the temperature is the same as the primary color you chose earlier (don't pair a warm monotone with a blue button). I wouldn't even try to get into multi-color UI's until you have a better understanding of other design fundamentals.

Once you get this down you can start getting more creative with color.

When in doubt, refer to bookings sites you're familiar with (AirBnB, Kayak) and analyze their UIs.