For UPSC Geography optional preparation, recommended resources include standard texts like G.C. Leong for physical geography and Majid Husain for human geography. Additionally, referring to the NCERT textbooks can provide foundational knowledge. Aspirants should also consider integrating current affairs relevant to geography, such as climate change and environmental issues, into their study materials. Other useful resources include maps, atlases, and online platforms offering study materials and coaching, which provide valuable insights and real-world applications of geographical concepts.