Candidates prepare for national and international issues in UPSC by following current affairs through newspapers, television, and online resources. Regularly reading publications like "The Hindu" or "Indian Express" can provide invaluable insights into both global and local events. Additionally, reports from organizations like the UN or World Bank offer perspectives on international relations and global issues. Participation in debates and discussion forums can also provoke critical thinking about these topics, ensuring that candidates remain informed and able to articulate their understanding effectively in examinations.