Raising one self-esteem can take work if we're not used to well, nurture it and/or if it was badly damaged by events of life. There are several things you can do to work on that, and I guess what's important is that it can take time, and taking this time is a good investment for your well-being :)
Self-esteem can be work on by doing some daily journaling. Not by writing what you do or think during the days and all, but by working on finding some things you can be proud of. You can try beginning with 3 things a day. It can be huge or small ones, just things that you managed to do, positive things.
It could be for instance "I did that task I was always postponing", "I managed to go out today even if I struggled a lot to do so", "I didn't talk down to myself" etc. It can also be doing a list of things you have accomplished, rather than the things you didn't or wish you had etc. Once again : it can be small things. The idea is to try and get a whole picture of yourself, because often, when we don't have a good self-esteem, we tend to focus on the negative, on the things we missed, we failed, etc.
Focusing on the positive is just a sane way to balance our view on ourselves a bit.
Identifying and living by your values can also be of some help : it's always good for self-esteem to feel right about who we are and what we do to be the person we want to be.
For instance, if you think preserving the environment is important, you'll feel better is you actually play a part in it, if you make your acts fit your values and thoughts.
I guess one other thing to pay attention to is to avoid comparison. It's easy to compare oneself to others more successful/smart/beautiful/happy/etc people. But comparison is the best way to feel bad about ourselves. Literally : you wanna feel bad ? Start comparing yourself to others. That's going to work, 100%.
So yeah, that's human, we tend to compare ourselves, and I guess it's a way of finding our place. Where am I in the whole picture, in the society. But we also tend to compare ourselves in a negative way (which is a self-esteem killer) or, for some people, in an overly positive way ("i'm better than others"), which.... isn't that great either... The only thing worth comparing ourselves is... with ourselves. How am I doing on the scale of "what I can do". And of course, we can't be "at our best" of our "global potential" all the time, and in fact our potential may vary from day to day anyway. I think we all do our best, or at least what we think is our best, every time. Depending on our level of energy, motivation, our mood etc.
Well, I hope it can give you some ideas. If you have the opportunity to see a psychologist / therapist who could help and guide you in your quest to raise your self-esteem, it could be great... It's always better not to be alone in this.. I guess you can find some ressources online from people sharing tips and ideas to work on raising your self-esteem.
And at any moment, if you think it's not helping or that you're feeling worse, then don't stay alone with it ok ?
An again : it's a long term work and it can take years, but it's totally worth it. :) Have a good time taking care of yourself !