how can i stop getting other people's mail by mistake?

theres been times when ive gotten someone elses mail by mistake, 2 wks ago, my maillady handed me my mail and when i was looking at the last one i thought it was mine so i opened it and found a check in it, i looked at it trying to figure out whos it was and it looked like a rent check so i gave it to my apt manager, another time yrs ago i opened my mail and there was a check for the office, she wasnt there that day so i put it under her door and wrote that i opened it by mistake and was giving it back, other times ive gotten neighbors mail and someone had all their credit card info on it, i gave it to my neighbor and told her i opened it by mistake, others have gotten my mail too, anyways to stop getting them, especially checks , its embarrassing to open them and to give it back like that. any suggestions?