In Japan, When speaking to a person, what are informal and formal ways to speak?

Question:

Informal and formal ways of talking to a person

Answer:

It's a broad question but I think I can help a little.

Honorifics: Formal (when speaking to people you don't know well)
Sensei
Shi (formal writing only)
San
Senpai
Sama (Higher ups only)
Ue
No Kimi (rarely used)

Informal
Chan (mainly females only)
Kun (mainly males only)
Kōhai (not really used as an honorific)

Note: There are loads more but these are mainly the commonly used ones.

Also, you may want to bow to someone to give off a good, polite and formal impression.
Maybe saying things like:

Ohayōgozaimasu - Good Morning
Konnichiwa - Good Afternoon/Good Day
Konbanwa - Good Evening
Oyasuminasai - Good Night
Sayōnara - Good Bye
Hajimemashite - How Do You Do? (Introductions ONLY)
Dōzo Yoroshiku - Pleased To Meet You (Introductions ONLY) / Please Do As I Requested (After asking a favour ONLY)
(O)Genki Desu Ka - How Are You?
Sumimasen - Excuse Me
Arigatō - Thank You
Dō Itashimashite - You Are Welcome
Hai Genki Desu - I Am Fine
Hai Okagesamade - I Am Fine, Thank You
Okaerinasai - Welcome Back
Tadaima - I Am Back (Now)
Itadakimasu - (Used when you start eating something prepared by someone or when someone has given you a gift, showing acceptance and gratitude)
Gochisōsama - Thank You, It Was Delicious (After eating ONLY)
Hajimemashite, Dōzo Yoroshiku - Please Be Good To Me In The Future/Pleased To Meet You (In inroductions ONLY)
____ (<-name) Ni Dōzo Yoroshiku - Please Give My Regards To ____

Hope this helped! x