I believe at the beginning of your life, self esteem is based highly on feedback from your surroundings. Getting praised, attention, and etc really either help build it or destroy it. As we grow older and become more aware of what others think of us it becomes a precarious situation since just a few peers who bully you can tip the scale but a lot of people still have great confidence in themselves and that's where the inside part comes to play. I don't think you can ever really achieve true self-worth without thinking about it yourself and deciding you are worth it in your own mind.

As for whether you should work on self worth first or fake it until you make it, I will say that people tend to be more attracted to individuals who look well put together. People who look sad, tired, and etc often just get passed by because they blend into the crowd and don't have much presence. Even by the way you walk and stand, if it demands attention and respect, you will get it. But if you can't convince your mind to accept yourself in a positive way, you'll always crave outside support more than your own ideas--which is a terrible way to be. The best is when you are just looking for positive affirmations from the people you care about. I'm firmly in the camp of: you have to move them together. Humans by nature are social creatures (on a varying scale but we still crave acceptance) so by working on your thoughts and then getting positive feedback you can begin to see the changes for yourself

And last but not least, there will always be rude and terrible people that can't look past what you look like but to be honest those people aren't worth your time anyway. If they can't understand you, chances are you won't be able to understand them either :P

Best of luck!