Take classes that cover world history and geography. If you are a high school or university student, you can probably take these classes as part of your regular curriculum. Adults can look for continuing education classes that are offered on a per-class basis at their local community college or university.
Focus on the aspects of these fields that are most interesting to you. Approach your instructor about undertaking an independent project or research paper that addresses your particular interests.
Find online or distance education courses if you prefer to stay at home, or if you live in an area without access to higher education.
Read some of the hundreds of books that are available on world history and geography. Visit your local library and ask the librarian what they have on the shelves that relates to your particular interests.
Take notes on the books that you read and keep the notes in an organized folder. This habit will help you to more easily find information from books you have read in the past.
Pay particular attention to the bibliographies in books about world history. Each bibliography will give you dozens of new suggestions about more related books to read.
Increase your knowledge of geography by studying maps. The visual clarity of a good map can teach you far more about the basics of geography than reading a text.
Focus your interest in geography on a particular area of the world and begin collecting more detailed maps that focus on that area.
Relate your study of maps to your reading in geography and world history. The study of the relationship of geography to history can be very fulfilling and enhance your understanding of historical events by seeing where they happened.