First you need to go to the property appraisers website to get the name and address of the owners. From there I would try to look up their phone numbers online. You can also put their name in the clerk of courts public records web site to see how much the mortgage is and if it is in foreclosure.
I would mail all of them a hand written letter in a white envelope or stationary. Just say you have and interest in purchasing their property. When they call you get the information needed to fill out the web form on http://www.wholesalehousebuyer.info (this is the new domain for the site to put your leads in)
After you do the research to see if there is a mortgage or not. The ones with no mortgage (free and clear) I would use a web service to skip trace them. www.Findtheseller.com may be one. Free and clear or low mortgages are the best.
Here is the 1st site - property appraisers http://www.hcpafl.org/www
This is the public records - clerk of courts http://pubrec3.hillsclerk.com