I would highly suggest just starting a franchise, it's the quickest way to learn. However, I wouldn't let this first chise be your lengthy one. Make mistakes, call guys up, send them down, adjust your roster a ton, and see how everything works. I'd then sim into the offseason after a few weeks (game weeks) to understand how the offseason works as well.
Everyone says "there's no wrong way to play OOTP" and that couldn't be more true. The game has so much complexity if you want it, so you need to know what options to hit or not hit & doing a dry run chise is the best way.