First you need to install a browser extension called Tampermonkey, which is needed to run the userscripts. Hereās the link for a guide on how to do that:
For your first userscript, you may want to install WaniKani Open Framework, which is needed for many WK userscripts.
After that, you can browse around the forum and install any userscript you like. I recommend not going too crazy when youāre just starting out. Someone already linked the Lesson Filter one, Iād also add the Double Check userscript which allows you to redo your answers when doing reviews. I canāt count the number of times Iāve made an error typo while doing reviews so itās a really handy userscript to have.