Before starting on a 0048 fic, it's best to do some research, which means having to listen, see, read and thoroughly understand how the idol system, especially a very large institution as AKB48, functions -- and the best place to start with is the AKB49 manga (which essentially functions as a sourcebook).
TBH, it's a different world right there.
EDIT: before I sleep, this is my take on the upcoming new documentary: