The best lies are almost truths.Keep your new general history as close to your actual history as you can but with just enough minor changes to plausably deny that was you if ever needed. After all a lot of people live very similar mundane lives and only small details differ.That way you are less likely to be caught in a lie (which you inevitably will be) since you dont have to remember a fake timeline....which I guarantee you will get wrong sooner or later and someone will notice an inconsitency.
Agent Smith