I've been 'graphic designing' (I guess) for not so long. I quickly became interested in typography (still am) I saw some of kurzgesagts videos and saw some really good typography. I tried to recreate it. And I did. I made some things I'm happy with. I made a few recolours of these, but my friends told me (and I agree) that this is getting repetitive and I should diversify. I am now stuck thinking what to to do. I remember I just saw the text on kurzgesagts video (check his video on string theory time stamps 0:30 and 2:30) and I just recreated it because I was inspired. But what do I do now? I want to get better at typography, but I have no idea where to start. (Also I use Paint.net because I cant invest money into software like Illustrator) I am very confused.
You have copied something you have seen. You have succeeded to copy the ideas, too, so you can make your own variations. Watch and copy more to make your palette wider, 1000...10000% wider.
Things called designs are made to create some wanted mood or to to give the wanted impression of something. The client tries to define the wanted mood or impression and the designer makes it happen. When you see ads or other designs, try to analyze what is wanted and how it was made to happen.
Pieces of art are different. The artist decides what is wanted. To create a piece of art one needs something to say by himself and a palette to present it.
Just now there popped out another answer. It seemingly has those a couple of things that I wanted to add + much beyond it, so I stop here.
Start systematic studies and good luck for them!
What about studying? Typography is much more than a group of combined sticks. This will help you to understand why those sticks make characters, what's the relation shape/space of each of them, what is the formal relationship between each of them, which are the typographic families, which are the systems of character measurement, which is the spatial relationship of groups of characters, among thousands of other things.
There are some questions and answers here about this subject: