What tough, personally-learned tip can you provide for a new channel starting out?

Recently, I ran a thumbnail experiment. I noticed lots of folks online put their own faces in thumbnails and I always thought it was a bit tacky. So I made two very similar videos, one with a content oriented thumbnail on one and a “reaction” oriented thumbnail.

Content oriented performed significantly better (somewhat confirming a personal bias, but it is what it is).

Now, several factors may need to be considered in this. Personally I think bigger channels have more success with putting their faces in thumbs because people have grown attached to their personalities. But for newer channels like mine, I would strongly recommend NOT putting your reactionary face in a thumbnail.