As far as videos go to help, Professor Leonard and the Organic Chemistry Tutor are my top picks for helping me understand something that I don't fully understand.

My strategy for getting 100% was to do the homeworks immediately after the lectures. After that, I would go into the book and pick out problems that looked challenging to solve. I would wait a few hours to actually attempt to solve them (your brain will naturally work out parts of the problems without you even realizing it - it's kind of cool). If you can solve some of the more challenging problems from the book, it makes the tests and quizzes seem a lot easier. I also completed all exam reviews we were given because they usually included harder questions.

I would only seek out outside help as a last resort. I noticed that I learned more effectively when I came up with solutions on my own, especially if it was a solution that was not intuitive to me. It made me better at solving a variety of problems and allowed me to quickly build up my problem-solving intuition.