Remove all decorations for 1-2 months
Keep tank bare as possible.
Don't feed for 2 days.
Associate your pressence with food, food, food.
After the first week, when hopefully he has learned this. Start putting your face somewhat against the glass(obviously not touching, your choice) and see what he does. Soon your buddy will start charging your face. Took mine 4 days, now I can't even stick my hand in the water without it being nipped on, FUN.