As @Tom said, contact a recruiter first. Then, after you have completed your written exam, (either passed or failed), I would recommend that you contact a trainer, they will get you up to speed with all of the procedures need to join. You can also start an ATC tracking thread.
Prior to the written test however, I would suggest that you look at all of the different tutorials on Ground and Tower frequencies, these are the ones that you will be tested on. I’ve linked a topic with all of the tutorials below:
My main piece of advice is to not rush. Take your time to get to know things, and make sure you keep practicing! I made the mistake of rushing when I started, and I failed every single test (don’t worry, I am a lot better now!).
Good luck!