roleplaying with a large group of people that you don't even know is too much of a hassle. it never ends well.
large groups do have an advantage, because you can rp with a large number of people, and that's fun. though large groups are not really ideal anymore in my opinion. new members could get left out, group leaders can get away with being bossy and rude, drama can happen at every inching moment there is an issue, there is often way too much rules and strict ranking (i hate that), and 90% of the members are barely online.
it'll be a good idea to join a rather small rp group. you get to know everyone pretty quickly and small issues can be resolved easier, and they don't turn into unnecessary drama.