Hey Felix, thank you for your questions!
This is going to sound extremely cliché, but I've always believed it to be the simplest, and most honest way. Just be you!
Those new subscribers that come to your channel, they've subscribed to you because they like what they see. They want to see what else you have to offer in the future! As long as you're being authentic, then you have nothing to worry about.
Try to make the effort to reply to those that comment on your videos and show support, or send you messages on social media and such. No matter how big you get or how much time of the day it ends up taking up, I think it's really important. I've never really considered myself to have 'fans', but 'supporters'. It's easy for people to forget that actually, these are the people that put their emotions and energy into supporting the work that you create. I've known people to become very self-entitled after getting a big following all of a sudden, and it's really very important to remain humble. Whenever I get a new subscriber, or a new comment, I feel like I'm building up my own little support network. My own YouTube family! I've always felt that 'fan' is a term that separates those supporters and the creator, putting the creator on some sort of pedestal. I've never felt comfortable with that myself. ^^
So, just stay humble, stay authentic, and put the energy into returning the love that people have reached out and given to you, and you'll be fine!