How do you pick names for your Sims?

Three different places;
Random Generator if I really don't have anything in mind.
Phone Book for last names
Baby Names on the web, especially if I am looking for a certain meaning to the name.

I write a lot of books and so I've always been a big fan of etymology. It's a little layer of detail that not a lot of people at all would notice, but I like the added flavour.

For certain Sims, especially vampires, I tie them to certain names from myth or particular events. If you know your stuff in that regard, you can determine what my vampires will look like in their dark forms without actually seeing them.

I call them as I see them.
Trash Kan
Sparks Fury
Gimme Cash
Mango Fruti
Etc

Or I give them snobby, classic sounding names.
Reginald Wedgwood
Elizabeth Dalefordton
Montgomery Lakewoodfield
The more ridiculous, the better.

I happen to have archived a lot of names in my brain, as I have had hobbies in the past that would require me to come up with names.

Aside from drawing inspiration from any and all kind of sources, I sometimes enjoy a little play on the names as well. For instance, spelling in new and humorous ways. Or making a name correspond with the personality of the Sim and soforth.

Most of all, though, I like to pick names that have a significant meaning pertaining to the Sim in question. For Sulani Sims, I give them Hawaiian names. Then I pick up some Hawaiian along the way which is cool. I enjoy educating myself when it comes to other cultures and languages.

It really depends. A lot of times I'll just use the randomizer, but a few times recently I've had a particular name in mind and used that. I've also named a few sims after Shakespeare characters because one randomized the name Celia so I decided to keep the Shakespeare theme going for her kids. Sometimes I also use baby name websites if I can't come up with a name, don't like any of the randomized names, have a sim of a particular ethnicity, want names that fit a theme, or want names that start with a certain letter.

Well, I'm a bit of a name nerd so I have quite a collection of favourites. I love looking up names and their meanings/origins. When I create a sim, they are often based on a character I have created in depth and named already. It can take me a ridiculously long time to choose a name that feels 'right' though. I like to pick names that are in keeping with a character's age/birth date and their origins/background. I sometimes look for appropriate meanings or just a name I like and feel suits the sim/character. Sometimes they also go by a nickname, for example my sim Rhys Hutchison has always been called Bunny by his friends/family. When my sims/characters have children (or adopt pets) I like to think about what names they would choose e.g. naming them after a loved one or a name with a special meaning or just one that suits their background. So, for example, my vampire sim, who is named after my favourite fictional character, was born in England in the 15th century, so the sort of names he likes are old-fashioned to most. He is a Music Lover and big fan of the Gilbert and Sullivan operettas too, so I looked up the names of the characters for one that was also very old and would appeal to both of us. He also lost his best friend Leo not too long ago so he would want to honour him in some way. Therefore his daughter is named Mabel Leonie. I definitely overthink names, but it's so satisfying when I find the perfect one.

I have a number of different saves and I use different naming systems in each of them. I also have a big list of surnames that I give to the townies so every one isn't called Yamaguchi. In my current save I am doing alphebetical generations using suburbs of major cities near where I live as first names.

@Movotti I wish you had been in charge of the game's random generator. Those names are names I need in my game. I think I have found a new naming system or two to add to my rotations. Thank you :)

I usually randomize the starting Sim's name but from then on, I go with the other options listed above. For some reason, I have this habit of naming everyone in a particular household so they have the same initials. I also use variations of the parents' names for the kids (i.e. Hank would have a son named Henry, ect). I also name the sims based on their parents interests. If I have a musical sim, I'll name their kids something musical like Lyric, and sometimes their pets as well. In my Westbrook legacy rotation, one of my sims was an artist, and I named their calico cat Picasso. Her daughter is a musician like her dad, and she had a cat named Sebastian for Bach. So it all really depends on the mood, the family, and what's easier. By the time my sims get married, I usually have a name for a male or female that would best represent the family.

I have a list on my laptop especially, for sims.
It has names I've seen or heard anywhere that I like or some I've come up with inspired by some other name.

In my country we have calendar with names in it. There are one or two names paired with a date. Marcela's name day is every year on April 20th. Etc. I simply go through the whole calendar and usually pick names taht aren't used taht much in my country.

If it is a foreign name I always google a top names list.