If he smiles at you from a distance, it's an invitation to approach him. (I'm assuming you didn't just forget to put your trousers on before leaving the house.) If he's smiling at you throughout a chat, it's a clue he likes you. Especially if he has a little smile on his face when you aren't even kidding. He might not be able to speak your language but that doesn't matter; his body language will tell you how he feels about you. If he keeps looking at you or waving when you are far away, it means he is interested in you. If you both happen to be walking down the street and he does this three times in a row, then he is probably asking you for a date! (Of course, there are other reasons why someone would keep looking back at you, so don't take this example as fact.) Looking back over his shoulder when you are following him indicates that he is not sure whether or not you are going to stay with him. This is a good thing if you want to follow up with him later. Waiting for you by the door after you have left a party also shows that he is still thinking about you. Scratching himself under his arm while laughing is a sign that a boy likes you. It may seem like a habit formed from playing sports but actually it means that he finds you funny.