• Right after the name.
• It is used even with friends.
• (Even when in English we wouldn’t use “Mr.”)

Examples

• クレイさん (kurei san) – Mr. Clay
• 山田さん (yamada san) – Mr. (or Mrs…) Yamada

Other name titles (used the same way)

• ～さま (sama) – very polite – reserved for those with higher social standing than the speaker. Also used for customers of stores
• ～ちゃん (chan) – used for girls and very young boys (kiti-chan = Hello Kitty)
• ～くん (kun) – used for young boys
• ～先生 (sensei) – used for teachers [クレイ先生 kurei sensei], doctors, and professionals

For now just use san. As you know from watching all the 1980s Karate Kid movies, it is the most common.