If I would like to rent a server, what should I care about? Obviously it should be hosted in the country I live in, but what else? I checked out a few offers (swissquake.ch, gameserver.4player.de, gameserver.gamed.de, gameservers.com) and they all look the same to me except for the monthly costs. So, should I go for the cheapest? Any experience reports?

If you pay peanuts you will get elephants.
Where do you live? Where do the players live that you want on your server?

I'm going to take a vague guess and say he lives in Germany >_<