How do you know a boy likes you?

there is a boy that is always bothering me, and smiling at me too i noticed how he smiles at other people, and the smile that he gives them and the smile that he gives me whe he sees me is wayy different,i told him that i like him b4 on the phone, but then said i didnt like him nomore and now i really like him and im not sure if he likes me back his always bugging, horse-playing with me and saying weid things like saying :oh, u like this boy: and different things,my friend hasa crush on him and everytime we are about to run into each other,and im walking with her and she sees him coming she pulls my hand to go a different direction so we wont run into each other,and something always happens that stops me from telling him i like him,and im not sure he likes me, so how do u no a boy likes u, gimee sme clues