One becomes a Youtuber by making videos. One becomes a popular Youtuber by making videos that people want to watch, and by being lucky enough that people notice those videos amid the endless stream of garbage churned out by wannabe Youtubers just like yourself. Start by trying to be somebody that people like to be around in general, unless you want to be known for drama and you want your career to end with you being sacrificed to the corn when the drama scene slows down. Make videos because you want to make them, not because you want to be Internet Famous. Be self-aware enough to recognize whether people might like your videos — to put it another way, make videos that you yourself would like to watch, and make sure you’re not so autistic that nobody else would ever want to see that shit. Be appreciative of any feedback you receive, positive or negative, because even saying “lol this video is shit” takes more effort than simply clicking to something else. Expect to fail at being popular; the odds are against you even if your videos are good.
And god help you if you don’t have a pleasant voice.