Even when I started I never took a massive loss bc I remember this advice when I first started and still use it till today
Manage position. YOLOling can be fun and anytime it works out like Roaring Kitty on GME, the gains can be big but there are more people who end up losing everything than wind up being that guy. I never put more than 3 to 5 percent in any trade. If it is a total loss it is not the end of the world.
Knowing when to take a loss. For me personally it is 8% but everyone has their own preferences. If a stock is down 8% something is going on that I need to take a look at. Even if I cannot find anything there still may be something.
Truth be told, 9 out of 10 times if I did that whole HODL approach it comes back and that's life. But that 1 time you lose 100% bc you didn't take a loss earlier you will wish you did.