Always using the same default bet sizing and feeling predictable. How to master pot geometry?

I recently realized my strategy is incredibly transparent because I use the exact same default bet size for almost every single hand. I have no idea how to manipulate pot geometry or maximize my expected value based on the board.
I've heard that doing a proper poker database review and using hand analysis guides can fix this, but I'm lost on where to start. What resources or methods actually taught you how to vary your sizing effectively and finally let the math do the work?

I never paid attention to my bet sizing and would just use the same default size for every single hand. It made my strategy incredibly transparent. The poker hand analysis guides on poker database review taught me how to use different sizings to manipulate pot geometry and maximize my expected value. Now I just focus on making the correct play and let the math sort itself out. which was something I struggled with for a very long time before figuring it out.