Sign up in popular social networks such as "Classmates" (, VK(, "My World" (, They are created precisely in order to help people find each other. Use the "Search" box which is usually located at the top right.
If you are a registered LiveJournal ( or in Diaries ( and you know the nick of the personwhom you are looking for, the internal search will check not only the user profile, but also his personal blog.
Download and install the ICQ program ( or Skype (, and then use the search by name.
Enter a query about the person you need to find, string to search any search engine such as Google ( or Yandex ( Press the "Find" button and carefully review appeared links. Possible, information about the desired person will be available on any corporate or personal website.
If you can not personally find the person by name, then go to the website of the program "Wait for me", sign up and leave there a request for a search.
Use various databases. For example, the base of MGTS.