One of the first places a paralegal can turn to start a search for a person is the website Accurint. This is a subscription service that is provided by LexisNexis, and is widely regarded as the database leader in the legal industry for finding people. If you know the person's name, last known address and some identifier (such as date of birth or social security number), Accurint is most likely going to be able to find the person you are looking for quickly and easily.
Another subscription service many law firms use is Westlaw. Using Westlaw's public records searches and People Map service, a paralegal can find past and current addresses, phone numbers, property information and more.
Check all of the social media sites for the person you wish to find as well. You could get lucky and find someone's work information on LinkedIn or Facebook. This will obviously save you from having to hire a private investigator and adding those additional costs to the case. Even if this data does not appear to be obvious at first glance, you might be able to find out where the person lives by reviewing the friend and comment activity. LinkedIn is a very good place for locating both people and companies and the states they reside in.
I have had great results just Googling the person's name. I then branched off depending on the search results and found quite a bit of information on the subject person. I printed out the Facebook page and twitter pages of the subject person and provided it to my attorney in charge and they were delighted to find this information to quickly!
Another good, and free, online people search tools can typically be found on your state's Secretary of State website. You can data mine these sites to pull voter's records, Registered Agent and Company Officer information, and even see if someone maintains any sort of professional license. All of these categories will typically list the person's name and an associated address.
I have found some success using whitepages.com also. If you have their last phone number, you could do a reverse search for the phone number and see what pops up in your search. Whitepages.com can also be used as the first try in obtaining an address of the person you are looking for and any of their relatives and neighbors. This is good for collection agencies and skip tracers to serve outstanding warrants and new law suits.
Lastly, if the person has a website or blog, do not forget to run the IP address through a free website such as: http://whatismyipaddress.com/. This will tell you immediately what city the person is in.
If you have any additional great resources you have found in your investigation, PLEASE feel free to post a comment below and I will update my post.