How do i overcome low self esteem?

ok, so today i was on the bus and these guys pulled up in a car next to it, and i looked out the window and turned around, then one of them was like was trying to get my attention and i was ignoring him and he told me my standards shouldn't be that high, and i dont know why i always take what people say so hard, sometimes i feel like a statue, good to look at, but nothing is goin on inside me, i mean stuff is going on inside me but it makes me miserable, i have no real friends. you know how some people feel good when the get a new hair-do, or outfit, sometimes i dont feel any different because i just feel people are looking thru me and can see how low my self esteem is, im shy awkward, dont say much, when i do say something its not spoken clearly, ugh, fml