I usually use two kinds of brakes. One is that after I stand up straight, my left foot swings straight forward and slides normally, and my right foot is placed horizontally behind my left foot (probably just behind, not very straight). The angle between my feet is about 90 degrees (in fact, an acute angle is enough), so I can use the friction of my right foot to stop it. However, everyone who practices speed skating knows that the grinding wheel is very expensive ... after a long time, the inner side of the wheel will wear more than the outer side, which will affect the skating technical action. The other is to stand up and put your toes inward, that is, walk a few steps like a splayed foot. Comparatively speaking, the second one is better for the wheels.
Actually, I rarely brake, but I usually stand up and continue to slide forward until its speed naturally drops. First, relax, especially when you are tired when doing anaerobic training. You should find your own opportunities to relax. Second, as the name implies, speed skating is too fast, the brakes can't stop … and it's dangerous, which is not good for your knees. )
I hope it helps you.