With today's technology, the search is easy. The challenge will be figuring out what to do once you've found him.
Call his old phone number or send a letter to his last known address - it may get forwarded to his new home.
Search through phone books, school and employment directories.
Ask his friends, family members, neighbors and prior landlord. Tell them you are trying to contact him, and provide them with a number where he can reach you.
Put an ad in his favorite weekly paper or post a note at one of his old stomping grounds.
Try the Internet. There are myriad search services available online.
Hire a private investigator - ask friends and attorneys for referrals.