How do 你 get a medal for a club?

I recently got a 'Deticated Fan' medal for the 'Barbie in the 12 Dancing Princesses' club. Before, I thought the same as you. But after receiving the medal, I think it's actually 2 things.
1. Contributions, like 你 said.
2. How long you've been in that club.

Hope this is right and helps.

The exact formula for gaining a medal isn't known (they don't tell us 或者 otherwise people would be cheating to get a medal). But it's known that 你 need to contribute to a club. Contributions which get a lot of 粉丝 and favourites, 或者 even just get 评论 on/voted on for polls/answered a lot for 测试 questions/looked at a lot, help. The system is a bit random. People can get 奖章 in 俱乐部 where they've only added a handful of items, but no medal in 俱乐部 where they're a lot 更多 active.