Ain't, too much informal?

What's up folks, is everything fine? I hope so.

I've been thinking about the way I'm going when I speak English, so, what I could notice was that:

- I'm quite often using "ain't". (informally talking)
- I'm saying "ni**a" too much. (informally talking)

What are you guys opinions about "ain't" and "ni**a" ?
Should I stop it ?

I have seen some English youtubers saying that, it's not good to say it.
I have this question because since i'm not a native speaker, I might sound so much desperate and forced.

Cheers!