Does your project focus on a specific/special population?
Access the government office or any organization concerned with that population to look for data.
For example, for health data on Veterans visit the US Department of Veteran Affairs website which compiles and makes available a range of data related to the health of this population (http://www.va.gov/vetdata/)
Consult the organization/departments website to look for links to data.
For example, the National Cancer Institute compiles and makes readily available data related to Cancer as a specific disease state (http://seer.cancer.gov/).
For example, the National Institute of Diabetes and Digestive and Kidney Diseases compiles data about diabetes and related conditions and health indicators (http://www.niddk.nih.gov/health-information/health-statistics/Pages/default.aspx).