What topics do you need?
What unit of analysis do you need?
What geographic unit do you need?
What time period/years do you need?
Knowing what you need is an important first step. Don't skip it! You need to have a strong idea of the specific data needed to answer your research question. Come meet with a librarian.
Who would collect this data?
When searching for data, think carefully about what organizations might have collected the data you need. Governments and international organizations often maintain and provide access to the data they collect, while businesses and independent researchers' data are less available to the public. For the later, subscriptions to data archives and business databases are sometimes a solution.
Here are some possible data collectors to consider:
Business & Trade
Don't ignore the scholarly literature (books & articles). Bibliographies and existing research may help you identify what types of data are available, and where to access them.
Statistics provide the numbers with which to understand the demographics of your community & to support an argument. You may want to start by searching the Department of City Planning site for a community profile. You can then find more detailed information about your community by searching American Factfinder by zip code. A source like ProQuest Statistical Abstract will provide you with national numbers that can help to provide a larger context. All of these sites and the others listed below have many features. Play around and ask a librarian if you need any help.