Assume that the future can change based on your actions, so any historical information that you bring along with you from the intervening 25 years may quickly drift out of the new realities history.
Edit: also assume that you can be given a healthy 21-year-old body if you want or take your previous self’s place.
Further, identification will be provided for you if you were not born at that time.
I assume I get ID for a person born in '78 if I choose the adult body? I was born, but very young.
Hard drives of data compatible with old computers, and a few modern laptops for good measure. Maybe some electronics equipment too in case I really need to interface with something obsolete or proprietary. Some period-appropriate cash to live on before my first “job”. The 2000’s won’t know what hit them.
I’m not going to be able to take over the world (shit, even taking over Afghanistan proved to be too hard), but I sure as hell can be a shadowy hacker figure that steers the course of history. I’ll probably avert 9/11 assuming I can get up and running fast enough, and try to steer China towards reform and detente with the West. Russia’s probably intractable. I wonder if I could tip the Florida election towards Gore, in order to get global warming taken care of faster. Giving a bump to renewables research could also help things along.
Edit: So, there would be a lot of phases to this, as I gradually shift from being anonymous to a hot item. Once I reach some point at or after present day, I’ll publish my archives so the world can decide for itself, and I’ll leave proof early on that it’s genuine, for example as hashes of data in things like newspapers that are well archived. Then I’ll dismantle my cabal and retire.