Are all your contacts in your phone by first and last name or just first?

Just as it suggest...Im curious how everyone organizes their contacts...Personally, I only put just first names and ill only put last names for people who have the same first name

First and last name.

First and Last in case of a duplicate name.

all my contacts have first and last name and are orginized by the first letter in their first name. I also add in as much info about them as I can

Good friends have a first name with emoji(s).
Girls I "talk" to have a full first, last and sometimes a middle name; with an emoji if they are "special".
Family is first and last name.
Co workers are first and last with a group tag so I can search the group and have them all show up.

The most important thing is to not mix up girls names.. That could be bad hahah

First and last name for everyone accept family who is just "mum" or "dad"

First and last name except for close family and friends

First and last name, and then the annoying girls that take my phone and change there contact with hearts.

All the info. I can get.