We can really speak from experience on this one. First and foremost, it's always a good idea to be mindful of what you show. Showing your face in and of itself shouldn't be much of a problem, though keeping your identity and private information out of the videos is a pretty good idea. Be careful what you show on the screen as well, always double check the videos. When it comes to having a good viewer base there are a few things to keep in mind:
1) Make sure the quality of the media is good. Doesnt have to be 4K but you want decent lighting and clear audio.
2) Be yourself and let that show!
3) Try and release content on a steady basis. Randomly uploading a video here and there is not the way to go.
4) Be creative! Re-inventing the wheel and simply making your videos the same as millions of others will hurt your chances here.
5) Give yourself time! A quality video in 2 days is better than a lower quality video in one day.
Just some tips, hope it helps