There are multiple ways to get started, but the easiest is loading up the default properties in a code editor and changing the values. Any editor works, but one that displays the actual color of hex codes are better.

Some good ones are:

My advice for editing these stylesheets is to try to mimic the way it works. If it says blue, do some shade of blue. If it’s stronger, make it be so. These labels are meant to make sense, and doing something completely different probably will look werid.

One really popular saying is to make the foreground lighter and the background darker. You can see this in many different UIs and websites.