I would first try to get bits somewhere (Pickpocket travellers but only rich ones) then I would go on to design weapon blueprints such as firearms, then I would probably learn about Equestrian culture, then I would try to get laid, then I would become a gun for hire with my guns designed for horses and At the end I would attempt to eliminate the princesses with my musket sniper rifle. Pretty much destabalize Equestria.