When considering resources for self-studying calculus, it's recommended to prioritize rigorous textbooks over simplified guides. Books like Stewart's are suggested for thorough learning, while the "Demystified" series is noted as a decent option but not the best. It's emphasized that practical problem-solving is crucial, and using workbooks alongside textbooks can enhance understanding. Older editions of established textbooks can be more cost-effective without sacrificing quality. Mastery of trigonometry is also highlighted as essential before tackling calculus, as it aids in understanding coordinate systems and formulas. Morris Kline's "Calculus: An Intuitive and Physical Approach" is praised for its depth, alongside Dover's "Essential Calculus." Caution is advised against poorly rated books like "Calculus Demystified" and "Calculus for Dummies," with recommendations for alternatives like "The Calculus Lifesaver" and "Schaum's Outline of Calculus" for comprehensive self-study.