This is something I've been working on lately too. What made me get into improving myself in this dimension was the book "No More Mr Nice Guy" by Robert Glover. This book pointed out the core of my shadow: toxic shame. This was my first step. I finally, after many years, had a word for what I was feeling, which helped me move forward.
Instinctively, I searched on YouTube "how to heal from toxic shame" and I came across a video where there was a practical demonstration of what I later found out to be self-inquiry (thanks to Leo).
I would say that every shadow has it's unique and distinct way of expressing itself, and it seems like there's so much, much more to my particular shadow other than toxic shame. So this is just an example.
My answer then, is:
1. Find book that resonates with your reality and see how it does, and observe your feelings
2. Self-inquiry
3. Journaling
4. Dopamine fasting
This last one is one I've recently started to practice. It's shocking how much your mind wanders and wanders and tries to stick to any wall it finds, like a fly, when nothing sedates it.
Hope this helps, and good luck