school time is a risky area. Showing minors without explicit parental consent in most countries has legal ramifications. Beauty... dont ask me, I'm a man. There seem to be a million make up people on YouTube already. Lifestyle? Do you have an interesting life? Do you live somewhere unusual? Do you follow an off topic sport? Do you follow an alternative lifestyle such as off grid or hippie vegan or biker?
Ask yourself what you enjoy, what you like to do, what you would like to share. Then make your videos.