Think about your research question. The data that you will look for will have certain types of attributes and information. Use the google doc and address these areas as best as you can:
Unit of Analysis (e.g. individuals, households, companies, players, teams, counties, states, nations)
Geography (e.g. parcels in a city, counties in a region, democratized countries)
Time Period (e.g. 1980-2006)
Frequency (e.g. annual, quarterly)
Remember not all characteristics may be captured by a dataset. For example, the availability of geography may be limited to data at a county, state, or zip code level. Try to account for data limitations and see how you might be able to address them.