Making your first pull request to a real project is terrifying. Nobody tells you how messy the process actually is.
Read the contributing guide first
Every project has a CONTRIBUTING.md or similar. Read it before you write a single line of code. It tells you how to format commits, run tests, and what the maintainers expect.
Start smaller than you think
I tried to fix a complex bug on my first PR. I should have fixed a typo in the docs. Start with "good first issue" labels — they exist for a reason.
Your PR will get comments. That is good.
Feedback is not rejection. Maintainers reviewing your code means they care enough to help you improve it. Take notes, implement their suggestions, and thank them.
The second PR is always easier.