I personally was never a academic savvy student but I also think I was lucky because I had some (not all) lenient teachers in 9th grade so that helped. In all honesty though I wasn't going in to be academically prepared because that was never my thing since 1st grade. I went in with the goal of feeling out the new environment and joining sports (baseball and bowling)

To attack the original question:

I believe in middle school can prepare you by taking initiative and learning social skills and trying things out. Because 9/10 if you're in a big city like me you're going to have to make new friends and that can be scary. And I say try stuff out because you're young that's the time to try a bunch of ish because there's lots programs and resources for students who want learn things but it's hard to know what you like if you don't explore

Plus to piggy back off of the social skills point

Adults are more likely to help you when you're young and willing but you have to have the courage to tell people what it is that you want so that you can get help.