First, you need to make videos like DanTDM Fan had said. Next, you need to base your content around a genre in YouTube (gaming, commentary, music, etc.). Make a video about the content and have a consistent schedule; good video editing software and good sound quality is recommended. Then, interact with your community! It’s good to chat with your community and see what they want in your channel. Listen to criticism! It’s good to consider constructive criticism to improve on being a YouTuber! These are some tips off the top of my head that I had mostly learned from other YouTubers. I hope this helps.
Also, don’t advertise your channel everywhere. It’s probably going to cause hate to your channel. I think it’s okay to share your YouTube video in your own social media account (like Twitter for example, maybe Tweet a link to your video). As long as it is not disrupting comments of other YouTubers or content creators, then you should be fine.