If you really want to see colour in action, I think Wasily Kandinsky is the painter to study.
Here's one of his abstracts. It's 127x200cm and was painted in 1925.
You can practice this on any zentangle or ZIA. I've used dare 39 by Erin Olsen to show what happens when you involve the three primaries. I did most of the colouring digitally because yellow is notoriously hard to reproduce on a normal scanner, but you get the idea! Following the scan of my original pen pattern-drawing, I have added the three colours one by one in the order Kandinsky chose. At the end I will add the two coloured versions I entered for the dare.
You can choose much subtler combinations of colours, of course. I love turqoise, so it appears in lots of my ZIAs. Mauve makes a good contrast. Add orange and you have a perfect trio of secondary colours (but orange is another colour that scanners hate!). You can also stick to monochrome solutions i.e. just add one colour to your drawing and otherwise shade wth graphite or pastel. Sometimes they are actually more effective. for scanning avoid metallics. They do not look good, but some cameras are able to reproduce them. Try your chosen colour combinations on a scrap of paper before attacking your drawing! You can use more than three colours, of course, but the more colours you involve, the harder it gets to harmonize them.
|dare 39, light grey shading|
|dare 39 +yellow added digitally|
|dare 39 (printed, some red added with pen, then rescanned)|
|red-yellow-blue (blue added digitally)|
|my monochrome version with orange (colour enhanced)|
|my full colour version|