Yes, AIF is shit. But it doesn't matter much. What people forget is that with most cert iii/iv things, it's just the book-learning part. You don't become a chef, chippie or sparky just by going to tafe, you do an apprenticeship as well. We don't have this structure with fitness, so you have to create it for yourself. Doesn't matter where you go to school, school is only the beginning of your education.
Firstly, you need your own experience. Barbells, kettlebells, gymnastics, state-level sports, running, whatever. You don't have to be good, point is you actually had someone coaching you, and went far enough that you got stuck and had to figure out how to go forward from there. Most PTs have never had a trainer or pushed themselves to any level.
Secondly, you need a method, a tool. Could be any tool, but it's just the way you'll try training people for a while. You do it for a year or so and then reassess, how useful was this tool, etc. This method may have a guru - Pavel for kettlebells, Rippetoe for barbells, Ross emanait for bodyweight stuff, etc - so seek them out and their followers and learn all you can from them, an unofficial apprenticeship master, if you like.
Thirdly, you get a job in a big box gym and every day you use those tools and talk to people. I was 4.5yr in community gyms, and every day I taught someone to squat or deadlift, and a few times a week I introduced a newbie to the gym, talking to them about their background and goals. Had I stayed in my garage or done bootcamps in parks or something, instead of dealing with 1,000+ people over those years it would have been 100+. I leave to others to judge how good I am, but I am better for having dealt with 1,000+ people than I would have been with 100+. Practice makes you better.
Honestly, if you can,
- coach a goblet squat and a pushup
- show up on time to PT sessions and
- record them in a journal and
- progress the effort over time
then congratulations, you are in the top 10% of trainers out there. But I think a person can aim higher than that...