If you've already watched Chad's, you can re-watch each section, but after that it all comes down to practice problems. Make flashcards of every single reaction that is on Chad's sheet, and memorize every single last one of them. Memorize all the different reagents (what they will and won't do, i.e. PCC won't do ratchet aldehydes, or at least I think that's correct, it's been since 2014 the last time I needed to remember any of this), and know the reactions from reactants--> products as well as products --> reactants. Go through the stack everyday and mark which ones you get right, with no cheating and no "close enough", only stone cold correct. Put those at the bottom of the stack, so that the ones you aren't remembering are on the top and you go over more them often.
This should be done in conjunction with the roadmaps. Roadmaps are a must, I don't care what anyone says. It's better to be over-prepared than under-prepared.
Let me know if you have any more questions. Good luck!
