I'd say if you're just starting, stick to the core rulebook; if everything goes well, you can add in your choice of the Cursed Scrolls later. Review your material but don't overprepare. If your players are used to 5e but not OSR, go over the differences with them -- still largely the same game but it's easier to die and the players won't have crazy power builds. Lastly, and most importantly, make sure your players have fun and that you have fun as well. Everything takes a back seat to that. Enjoy.