As with anything, the only way to really improve is to practice. Practice using different techniques, angles, everything! Watch a tutorial online and then go try it out! Once you become comfortable with an aspect of lighting, technical aspects of your camera, or finding interesting light it will become part of your bag of tricks. You'll be able to reach in and grab a circular polarizer on a sunny day or adjust fill flash at a moments notice without thinking about it.
Having a big bag of tricks only comes through repeated practice and work. That can be from assignments, assisting, or trying things out on your own. The best way to get better is to shoot more and be aware of how and why you're shooting. Check in with yourself and make sure you aren't staying in a single position for an entire game or that you are trying to capture different elements and aren't just getting the same photo over and over again. Ask yourself, "How can I make this better?"
With so many uncontrollables it is hard to have a great shoot every single time. Practice and a big bag of tricks will help out tremendously. You'll know how to deal with bad situations that arise, how to get the "look" you want, and to get a safe shot before trying something a little more risky. The great thing about a bag of tricks is that it's never complete. There is always something more to learn. I'm still trying to be completely comfortable with many different aspects of light painting and need to explore different techniques that help get my desired effect. Get out there and shoot some more!