All I know is what I've read in novels.
Say John Jameson needs to disappear but doesn't want to run or hide all his life. He wants to live in the open, just not as John Jameson. That's your situation, right?
First he needs to find a person who was born about when he was and who died in childhood. It helps if they're the same race and religion. Ideally, the name is no more unique than his real name. He would write to the county clerk's office (in the US, anyway) seeking a replacement birth certificate for the dead child, Bob Robertson. On receipt, he leaves the address where it was sent, leaving no forwarding address.
Now he needs to do a few things at once. One, change his appearance in a way that he can maintain. He grows a bushy beard, or shaves his head, or gains eighty pounds. He starts wearing contacts instead of glasses. He gets tattoos over distinguishing marks or scars.
Two, he establishes himself as Robertson. Once he looks different, he gets a drivers license and a credit card, which he uses and pays off, establishing a decent credit history and higher limit. He uses that card seldom after that--it's for emergencies.
Three, he gets work that's completely unrelated to his skills, education, and interests. If he used to be a truck mechanic, maybe he becomes a janitor or a short order cook. He's likely to be severely underemployed and poor as a result. He's got to live very simply, in rented room, traveling by hitchhiking or bus.
Four, he makes zero contact with people from his past, not ever. No phone call or post card saying he's okay, nothing. He will never see them again.
Five, he moves often, maybe every six months or so. He pays his rent and buys his necessities in cash, which is untraceable.
Six, he's a law-abiding citizen. He never steals, gets in fights, is publicly intoxicated, nothing.
Seven, if he's smart he'll get a new identity or three, ready to be used if someone recognizes him.
Eight, he never again pursues any of his former hobbies or interests. If he was into model trains or football, he isn’t now. He’s a homebody, going out very little, since that increases the opportunity for someone to recognize him.