To choose the the right group/roleplay, you will need to, first figure out which direction you want to go. Second, if they active or not, and third find out if they're accepting the certain characters you currently have. To await for a good group, I personally wait until it has certain number of members, to make me sure that it is active. Secondly, you want to search for the group members who are helpful and nice. You wouldn't want a fussy person to boss you around and make you unhappy, right?
It's not hard finding one unless your looking for some advance or something willing for your taste; everyone has different tastes, especially if your a roleplayer. You need decide if you want the rp mapped or not, before looking around. There's plenty of groups that are mapless but sure know how to make things interesting. Personally, I like groups that have sites which could keep updated constantly. It's better because they probably hold contests or announce new plots; those are always the best.
Since i ain't a big fan of roleplay, I usually like to find a group is more chill than ongoing -I like to meet my group strangers and talk to them, in order to understand them more. Usually, when I join I just join because it seems interesting - I hardly focus on the plots. And if i find the group going slow or just well as before, I will leave.
To sum this up, all groups are good, not great. Good. I'm sure there's something new you look forward to and immediately join them. But if they were to meet my requirements, I would mostly say nice and just overall fun.
