I have cleared both these certifications in first attempt and the only material I referred to was Scrum Guide and Nexus Guide. I read them so well, understood it word by word and relate to my real experience while reading these guides
I also ensured I scored 100% three times in a row in open assessment for both certification before I attempted the real assessment
Understand every question scenario in test and eliminate the incorrect choices that go against the scrum rules responsibility events framework and you will arrive at right answer automatically.