Depends on exactly what you mean by branding, but I'm going to going to guess you mean your style/personal touch? The greatest thing you can do is be yourself. Stick to a genre or two. Basically, be consistent so your viewers know what to expect. If you know what you want to do, find what makes you doing it unique. Sometimes you might do this in a "clever" way or it might be so simple as something about your personality or experiences that makes it different than YouTubers X, Y, and Z. Basically, what is something unique about you that puts a different spin on your topic? Expand on that and you'll be finding your brand in no time!