Note: You'll see german language in the Screenshots

I keep this clean and simple and i assume you already use Git and know where your Git folders and World of Warcraft \ _retail_ \ Interface \ AddOn folder are. I will take ElvUI as an example.
The big advantage is, that you don't need to copy your folders now everytime you pull the new changes.
- Delte your existing "ElvUI" & "ElvUI_Config" folders from your World of Warcraft installtion.
- Open the windows command prompt as admin. Type in the windows search: CMD
- In the Command Prompt now must use the "mklink /D" command (Symlink)
In the first part, we need to tell the link where you want your folder, so it should be the World of Warcraft \ _retail_ \ Interface \ AddOn folder:After this, we must tell the link, the path to our existing git folder:The whole link now should looks like this:If you hit enter, it will create a new folder called "ElvUI" in your World of Warcraft \ _retail_ \ Interface \ AddOn folder and use the existing git folder - The same step you'll need also to do with the folder "ElvUI_Config":