Personalizing my desktop and mac environment makes my life just a little more enjoyable 
As of 2022, this is what I have customized (Note: a common theme is the color pink):
Terminal
Edit the .zshrc file for a “welcome banner” on boot. Preferences to make a pink and black theme. 
Spotify
I use Spicetify to make my Spotify GUI pink, using the Ziro Theme in Rose Pine. 
Desktop Folders
On MacOS, folder icons can be changed to an image of your choice. I’m currently using various transparent images of flowers.
VS Code
Visual Studio Code is my text editor of choice. Their website has instructions on how to apply themes. I personally like the Pink-Cat-Boo theme.
[Note: This post was edited on Jan. 5, 2023. Pictures were added.]