I'm single and am 20 years old and i go to visit my sister often at her apartment. She lives in an older folks building and there are tons of young people that live there now and there is a lobby as you go into the apartment building. I've started to notice this really cute guy around my age always hanging out in the lobby and he lives a couple of doors down from my sister. He is never with anyone and seems to be a loner. However, i only see him maybe once or twice a day. He is friendly and he'll say hi or he'll help me with my sister's baby by opening the door. He is always around when i'm around and one time i was in the lobby with my sister's baby waiting for her to come through the door because she was driving home from work and i was watching the baby. He opened the door for me and then said for me to have a good night (cause it was nightime) and then he left. I really like him and don't know if he likes me or not. I don't know how to send him the right signals that i'm interested. I need advice!