You know, this question is pretty well-known:
"How do I get promoted to [insert your rank here boi]?"
Well, once you ask that you might get the same answer:
"Get trust", or something like that. Maybe "Be trusted".
If you really do want to get promoted to, for example, Grief Police, think twice.
Maybe thrice if necessary.
Think about these questions:
1) Am I helpful and friendly, do I really deserve getting promoted?
2) Do I know how to use for example, Logblock and many other commands? People may ask you questions, and you can't just say "I don't know, really. Ask another moderator." (If you're grief police, you don't need to know the moderation commands for example, /tempban. This is pretty obvious.)
3) Am I well-known? I cannot just go "Hey I just recently joined now can I get promoted I am helpful!!!".
4) Do I have to work too hard in my opinion, will I engage to protect the server from trolls/griefers etc.?
Ok, this is my opinion about getting promoted. Opinion, got it?
Discuss about it. I think I did forgot some important questions.