Hi, Vickie,
I'll tell you what worked for me. I wrote and wrote, but I read and took risks. I tried new things. I allowed myself to be cringe and fail to find what works for me and my style/voice. I got feedback from trusted "readers," i.e., other writers who know how to give feedback beyond what their taste/preferences tell them, which is irrelevant. The combination of feedback, reading, and continuous writing helped get me better over time.
How did I know it? If you look at any piece of writing from 6months, a year, etc., and cringe a little at it or know how you'd fix it or rewrite it, it means you're learning.
Hope that helps,
Felicia