you should join Krems clan, we are best clan EUW and NA so naturally we are the only clan worth joining
I'll give you a quick run down of some of the clans that I can remember
Druzhina (DRZ): Primarily Russian clan, better speak Russian if you want to join, or just scream cyka blyat and they'll let you join
Grey: I think these guys are Polish? I can't remember too clearly. Nice clan to join if you can get in, but I'd recommend speaking Polish.
Kapikulu: More Russians, however these guys teamkill everyone by accident, so be careful around them :O (This clan is pretty much dead, I barely see any members)
Vanguard: Two old clans merged together and formed the Vanguards, the two former clans were Byzantium and Nords.
Krems: Wacky fun clan filled with hilarity, Krems don't really take the game too serious, they're more inclined to have fun than anything.
Mercs: Fairly serious clan, however they're invite only so don't expect to get in this clan easily.
Barabe: I don't actually know where any Barabe members are from, so I couldn't tell you that, I don't think they're a region specific clan anyways, but they're a cool clan with serious and fun mixed together.
Templars: Another fairly serious clan with a few fun members mixed in, they fight for the god known as chadz.
Kingdom of Northumbria: Viking style clan similar to what Nords were like, good clan to join if you can get accepted, you might have to message a leader though.
Bogumilli: These guys are a pub based clan, so they should accept you without much trouble, I don't see many members on the server anymore but it's still a good clan to join, they have an armoury stocked with things you can use.
Strategus isn't all that good for a new player, for one you need a fairly complete build to stand a chance of doing any fighting, plus the strategus is clan dominated, so you'd need to join the clans that take part in the Strategus scene to have any hope of doing any good, overall I'd say don't bother with Strat, it's not worth it.
Hope this information helped