Okay. There's always a room for growth and there're some new things to learn. So the question is. Where can I find some good and interesting articles about sales/sales techniques/sales tips and tricks?

For sure. And degrees won't help here. You can only learn by solving the problems, mastering new tools, and trying to find relevant infromation. By the way, I think there's something I can share here. Here, check this article https://revenuegrid.com/blog/personal-selling/ . There're some very nontrivial suggestions there. And it isn't a random website with random articles, just visit the website and you will see what is this.