I think the first thing you should do is to check to see if he is someone else's pet. Take him to a vet or shelter to have him scanned....he may have a microchip on the back of his neck. Check all available sources---vet offices, classifieds, shelters to see if a lost cat matches his description...someone may be looking for him. If you've done all that and can't find his owner and you've decided to keep him, have a vet check him over, gets his shots, get him neutered. Good luck!