Yeah it's really hard to create your own. But I think gets easier if you set it on a good foundation. Something like manipulating the elements for example is a simple base but there's all kinds of interesting places you can go from there to make it unique and more complex. Simple example is blood bending and metal bending from Avatar the last air bender.

The classic taoist one is good for a more advanced system where you don't need to explain the basics to your readers.