Tips for homework you should do in advance and then how to word a good request letter.
Finding data
Data terminology
Before you ever start your analysis
Tipsheet: How to use the Minnesota Government Data Practices Act
Tips for writing a good data request letter
Building your own data Lessons learned from building databases with colleagues How we built a database from thousands of police reports
Finding the right demographic data
Census: A guide to the perplexed (by Paul Overberg)