For me, the most important thing to have first is passionate about it. If you truly want to be a successful YouTuber, you need to love what you do in the first place, if you already have that, then you can go to technical related stuff, like preparing good camera and stuff, deciding what kinds of content that you want to make, and don't forget to do some research about popular videos around your are/country, it helps with creating some
 video ideas.