Obtain academic study materials related to economics and economic development, which can be found inexpensively from online booksellers and auction websites. While your focus may be on development, you absolutely must have a solid grounding in the basics of economic thought. A general economics text (such as a text used in an Economics 101 course) is essential because it will allow you to review and refresh your understanding over time.
Read through the basic economics text, paying close attention to both the macro- and microeconomics section. Take notes on aspects you consider important, and, at the end of every section, review the pertinent aspects of what you have learned. Move on to basic texts about the economics of developing nations, continuing to keep a review notebook for constant review.
Move on to more advanced texts in economics and development. Try enrolling in topical economics courses at a nearby university or college to help ensure you have a comprehensive understanding of the aspects that interest you. Expand your reading and research to include a variety of economic views on various development issues, as there are many schools of thought on these matters. Write short pieces comparing the various systems, comparing their predictions to various real-life events to see how they hold up.
Enroll for economics and development newsletters, reading lists and resource databases online to access scholarly papers focusing on your areas of interest, which will allow you to keep up on the most recent trends in economic thought. Always remember to compare the predictions of theory to a variety of real-life trends and developments to keep yourself grounded.