Probably the thing I did that had the single highest impact on my self esteem was an exercise where I had to do something nice for random people (including those close to me) for thirty days, once a day, and if I get caught it doesn't count.
It was easy to do nice things for people, not "getting caught" or telling anyone nearly broke my brain and indelibly changed me forever and gave me a much clearer picture of what I did and why, and what my motives were for "being nice" to people.
How it was explained to me was if I wanted good self esteem, I needed to do "esteemable acts' but before I could do those, I needed to learn what that really meant, "esteemable acts' that I derive a gain from aren't esteemable.
It really made a vast difference.
PS I also agree with GL, the other thing I need to do is stay away from people that tear me down, because eventually I believe them.