Basically what Sifra said, but I'm just going to add in my experience (since I mask anime frequently and my, uh...interesting method has worked for a lot of people.)
First off, when you create a new project file, CHANGE YOUR FRAME RATE PROPERTIES. Most anime is in 23.976 IVTC FILM. If you don't change it, masking will most definitely glitch out, and you'll be masking more frames than necessary.
On to the mask. Before you start masking, right click the video and hit "disable sample properties" or something along those lines. This will stop the clip from glitching when you render.
Finally, the actual process of masking! This might seem tedious, but it's a way to make sure your masking turns out nice. Most animes are animated in 3 frames per second, meaning that there will be 3 keyframes that are the same. Mask, drag your timeline and, even though the mask doesn't move, add keyframes to hold that space so that the mask doesn't try to follow the general outline you created. Because anime is 2d, the motions are subtle but drastic? If that makes sense? Anyways, when it's finally time to move the anchors: don't. Don't move them. Reset the mask and redraw to avoid wobbles.
It's tedious, I know, but you'll get the hang of it. Good luck!