My €0.02 is this.
The key is to find a group of like minded individuals whose company you enjoy. Chances are they are already out there. Finding them is just a matter of trying out different servers and seeing where you like the players. If you hang around a server long enough you will bond with some of the players there and the rest should work itself out from there. Chatting and teamwork will speed that process up.
Whatever you do don't go join some 12 year olds kid's "clan leader" wet dream that will fall apart in 1 week with lots of drama and grief all around. It will only piss you off and waste your time. You will have a lot more fun with a team of level headed individuals who will be around in 6 months. This kind of team also has a lot better chance of success... More fun equates to more playtime and thus better results and a deeper level of immersion in the game which is what I assume you want from a clan.
Of course if all you want is a clantag feel free to join any of the masses of overnight clans organized by the aforementioned 12 year olds. They also usually have to lowest standards for acceptance.
