Quoting SunFlowerSeed:

How to address people in Turkish?

There are many factors to choose the right word to address someone. I will divide it into 3 sections for now, according to age.

0. Among friends anything you LIKE.

1.YOUNGER than YOU
Hey! Bakar mısın?
Çocuk (-ğum) --> To any kid.
Genç --> To any teenager.
Oğlum --> To a boy.
Kızım --> To a girl
But you should be old enough, say over 40, to address young people with oğlum or kızım. It can have side effects if you are not old enough.

2.of the SAME or SIMILAR age
Arkadaş(-ım) --> Friend.
Kardeş(-im) --> Bro or Sis.
Bayan --> Sis.

3.OLDER than YOU
A- Male Addressing.
Beyefendi --> To ony male person, especially to show your respect.
Abi/Ağabey(-ciğim) --> Who looks little bit older than you.
Amca(-cığım) --> Almost anybody, who looks 20-25 years older than you. Practically over 40.
Dayı(-cığım) --> Same as Amca.
Baba(-cığım) --> Fathers of your friends. If you are accepted as a son or daughter into the family.
Dede(-ciğim) --> People who are older than 70 years old.

B-Female Addressing.
Bayan --> To any female person which is under 40? 50?
Hanımefendi --> To any female person which looks older. or to show your respect.
Abla(-cığım) --> Who looks little bit older than you. Less than 40.
Teyze(-ciğim) -> Almost anybody, who looks 10-20 years older than you. Practically over 40. 50 is better in case of females.
Yenge(-ciğim) -> Wife of a person that you KNOW.
Anne(-ciğim) --> Mothers of your friends. If you are accepted as a family member in their families.
Nine(-ciğim) --> People who are older than 70 years old.

Females can take it offensive when you address them teyze or nine. Better to be careful.

Age difference is important in all addressings.
You cannot address someone amca if you are 30-35 and he is 40-45. Or you cannot use dede even for a very old person if you are over 50.

In my experiences,
I call one of my friend's father as ABI.
Because I feel close to him and he feels close to me.
But call that friend's mother as YENGE, instead of TEYZE, as addressing a friend's wife.
And call another friend's father as BABA.
Because I have a very good relationship with all family and they accept me as their son. I also call mother as ANNE.
And call any other person's father as AMCA, and mother TEYZE.


OFFICIAL ADDRESSING:
Official addressing is used against official people.
At official meetings, at official places, at work, at school, in vehicles etc.

Usually it is done by adding Bey, Hanım to listeners official title.

xxNAMExx bey -> Any worker, if you know him by name only.
xxNAMExx hanım -> Female.

Patron -> Your boss.

Müdürüm -> Your manager.
Müdür Bey -> Other managers.Male
Müdüre Hanım -> Other managers.Female

Şef - Şefim -> Chief of your department. Or in restaurants, chief of waiters/waitresses.
Şef bey -> (Not common) Chief of other departments.

Memur bey -> Any people working in government. Can also be a police officer, a clerk. Not the lowest degree like cleaners etc. and not a higher degree like müdür or above.Male.
Memure hanım -> Female equivalent of memur bey.

Polis bey -> A police officer.
Komiser bey - komiserim -> A police chief.

Öğretmenim -> Your teacher.
Öğretmen bey -> If you are old enough and want to talk to a teacher about your kids etc.Male
Öğretmen hanım -> Female.

Şoför bey -> Any driver.Male.
Şoför Hanım -> Female drives.
But you cannot address any driver in the traffic with Şoför.
It should be their job to drive.
For common people driving their cars, you should use age technique to address them.

Kaptan Şoför bey -> Can be used to address long-distance bus drivers. Not very common though.

Garson -> A waiter, a waitress.
Tezgahtar bey/hanım -> A seller in a shop. Not the cashier.

Efendi or xxNAMExx efendi -> Root is Efendus from Greek language, meaning an intelligent person.
Although it is used to address people in higher statue than you in old Turkish, it is not nice to use it addressing higher statue people nowadays.
You should have a higher statue to use this. Generally used for common workers by their managers, boss. Male.
***My advise for foreigners is not to use it, unless you are working in a Turkish company with a higher title.

Most of the addressings can be made more frankly adding -m (my) or -ciğim(cute ?) suffix to the word. -ciğim suffix can be improper to use when addressing strangers. Though you find him/her cute, he/she might not find you cute enough.

*But pay attention that Efendim? is not an addressing word, it is used to tell the talker that you didn't understand/get what he/she told. Sometimes can bu used instead of simple ALO on the phone.
**Efendim is also cen be used in replies to higher statue or age people.
Evet efendim. - Hayır Efendim. - Tabii ki efendim. etc
***There is also 'efendime söyleyim...' Used to get some more time when talking, or to show the listener that you need some more time before adding new items to a list when talking on a topic and after getting to some point in that.
I mean you cannot start a conversation with it.
*****You can also use 'efendim' for addressing in a conversation. But it is not common to address people with efendim at first.
- ....after some talk....
- efendim, şunu da belirtmeme izin verin. etc etc