Self esteem is part of inner game. You have to start knowing that you are goodlooking. When can start knowing that you are good looking is the only time when you can actually start getting anywhere.
There are many resources out there and are many game routines but many of them are very closely linked with the confidence factor.
I know this because right up till my senior year I had terrible game and I always came up with excuses like "I have a minor acne breakout this week, ill approach her some other time" or similar appearance factors. I did this all the while I was told i was attractive by women who I thought were just saying things to make me happy.
A few years later and I am starting to realize that if you go into every interaction with the mindset that this girl WANTS you and everything she does shows that she WANTS you in some way or another, you will be massively more confident in conversations with women.
But Confidence is step 1
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"Always desire to learn something useful." - Sophocles