Okay, this time, I want another follower besides Faendal who can teach me archery. I was wondering if it is possible to have Aela as a follower after the werewolf mission.
Yes, you can. Additionally you can also marry her, but that's not what you're asking.
I'm not sure what the requirements are to get her as a follower - whether you can get her straight after the first werewolf mission, or if you have to finish the entire Companions questline.