1) Are you the author?

2) Just a fan of the project? A family member? A friend of the author? (I don't care about the details, so if you want to keep it secret it's fine for me. Just reply "2".)

3) You just found it and think it's good?

There are some initial recommendations in https://news.ycombinator.com/newswelcome.html and there are also the guidelines and FAQ linked at the bottom.

Also, there are additional recommendations written for YC companies, but the advice is good for everyone. Just avoid the specific parts, for example do NOT use "Launch HN".) https://news.ycombinator.com/yli.html

Just remember: avoid hype, avoid automatically generated text, avoid very short comments and avoid jokes.

Wellcome!