Bowing
Bowing is a very important custom in the Japanese culture. It can express many meanings, including respect, gratitude, apology, greeting, etc. Don't assume you can learn how to do it right. A simple inclination of the head is enough for foreigners. This form of etiquette is very complex. The depth of a bow can depend on the social status or age of the person the individual bows to.
Honorifics
The Japanese language uses a broad array of honorifics to address people. These honorifics are usually gender-neutral, though some are used for both genders. –Kun is primarily used for males, whereas –chan is primarily used for women and can be attached to both first names as well as surnames.