Good with Faces. Bad with Names

I have come to the realization that I SUCK WITH NAMES!! There are so many times I have been greeted and I have NO IDEA how I know this person who is so kindly taking the time to ask me how my day is going. I was walking past the post and a friend of mine, Katiku, was talking to a man. So I went up and greeted her and the man. Then he told me “you owe me something, do you not remember” I just stood there because I had not a clue what he was talking about. Finally after what felt like 10 minutes I said “I am sorry can you please help me I do not remember”. Turns out he is a teacher at one of the schools I work with. I felt so dumb I borrowed a dance outfit a month ago! Katiku thought it was hilarious but I was mortified. I have been here a year and I still do not know too many peoples names. I need to come up with a better system!! ANY IDEAS?!?!