I think the most important principle I try to stick to is trying everything, and often. I've experimented with just making photographs that play with only analogous colors, so everything basically different shades of one color, like red for example. That one is one of my favourites, but can be extremely hard for me to pull off. It's why not much of that work gets shared, cause I've definitely failed more than succeeded.
Other times I like to keep it simple and play with complimentary colors, so opposite colors on the color wheel. Easy example, red and green. I like to keep in mind that warm colors can appear closer, and cooler colors, further back. However, it's also fun to experiment with switching them and trying to make it work. Once you know the rules, you can learn how to break them effectively.
Playing and experimenting are the only way to really master anything. Do lots of it, fail more than succeed, and just keep at it. I look at the things I'm afraid of and I run at them instead of away from them. I can't help it, I think I blame growing up on horses and being bucked off and having to get right back on the horse. You can't let your fear or discomfort win, so you just learn to be comfortable in both.
Below and example of loosely trying to play with analogous colors. Everything is some shade of yellow. I wouldn't call it a success yet, but I enjoyed making it.