Since mALX mentioned her difficulty in making faces in Fallout 4 in another topic, I decided to create this one to concentrate on mods for appearance. I found Fallout 4's chargen to be tough at first, mainly because of the vanilla game has no list of options of what you can alter. I literally had no idea there were separate options of Full Mouth, Upper Lip, Lower Lip, and Mouth Corners. So my first mod is the one I consider absolutely essential:
Fallout 4 Script Extender = Needed for the next mod, plus others for the game.
LooksMenu = This gives you a list of body parts to choose from when creating a character, rather than playing hunt-the-pixel by mousing over every speck of your characters face to see what you can change and what you cannot. It also allows you to save faces to preset files, and import them. Sharing faces has never been so easy!
Valkyr Female Face and Body Textures = A much more natural-looking texture. Not as plastic and shiny looking as the vanilla textures are. There are other, newer texture mods out, but IMHO, none look as good or as natural.
Ponytail Hairstyles = From our old friend Azar. Because you never want the vanilla hair in a Bethesda game.
CC's Improved Hair Colors = Because every hair color in the vanilla game is brown.
512 Standalone Hair Colors = Does what the name says. It adds so many new hair colors it can hard to pick one. Many are just ridiculously over bright. But there are still a lot of good ones in there.
True Eyes is the eye mod I use, but the author has taken it down. I really don't have any specific recommendations for mods to replace the vanilla eye colors.
Glowing Eyes adds a bunch of - you guessed it - glowing eyes. Handy for playing a cyborg, mutant, or supernatural character.
Oni cute asian face parts = a small mod that alters the head files, to give a more Asian look. It is really subtle, so I use it for all my characters.
That is all I use. There are not as many options for Fallout 4 as there are for Skyrim. However, one great thing about F4 is the ability to save presets with LooksMenu and upload them to the Nexus, and likewise download them. I often use presets I find as starting points when I am creating a new character, and then spend twenty minutes or a half hour tweaking to get them how I like them. However, I often find that presets that looked great on the Nexus look terrible in my game. I think that is because many people use a ton of mods, as well as things like ENBs to change to how the graphics look.
Using a preset it easy. It is just a single .json file. Put it in your Fallout 4\Data\F4SE\Plugins\F4EE\Presets folder. Then in character generation click on the Presets option at the far left. It will bring up a list of all the presets you have to choose from.
I have some presets on the Nexus:
Hecate
Victoria
Killer Frost and Caitlin Snow
Annie Ley Oak