Minecraft server donations legal concerns?

I have a minecraft server that I pay $10 a month to run on mcprohosting. I want to have a donation system where I can get money to upkeep the server. I was wondering how level it is or what I have to do in order to accept donations. I see many servers dining this so I'm wondering how I can do it without getting in trouble with the law. (Btw I'm in the US)

If someone gives you a donation, its not against the law. They are basically giving you a gift and therefore should not expect a refund if they ever try to take it back. If you promise them something for their donation, then you must deliver. If you ask for a donation just to support your server, than you don't have to give them anything. Most servers set up their donations through a website, like Enjin.