For those who are not using mods yet and are interested in doing so:
You'll have to download BepInEx first and then just install the mods you want (most of them can be found in Thunderstore). Using the ModLoader to install everything from Thunderstore should be easy enough.
To install it manually, drag and drop all of BepInEx's files into the game's main folder, open the game once and close it. BepInEx should have generated new folders inside its main folder after that, and one is named 'plugins'. Just the mods' unzipped folders inside plugins and that should be it.

Popular mods:
>AppearancePlus
Lets you edit the max/min capacity of body sliders, adds a command to change your character's size and other miscellaneous stuff. Its beta release also adds a few new emotes.
>Homebrewery
Allows to add new armor pieces for vanity purposes, new dyes and new consumables with custom effects. Although it comes with a few items by itself, so you'll need to add more stuff from other mods.
It also adds a new cellphone feature that allows to change your physical appearance (free of charge) and check Spike's on the spot. Either download it from Thunderstore or from the Mega pack (which already includes almost every armor pieces ever made, but it's an older version which not allows custom meshes for the sake of fast loading.)
Mega pack: https://mega.nz/folder/jR4ExajI#gFKKyoRFVDBJX9SL6nzRMA
>MapLoader
Allows custom maps. Max 12 custom maps at the same time. The maps must be downloaded separately.