<Snipped quote by Dinh AaronMk>
last time i tried for a prussia game, i annexed hamburg and basically everyone declared war on me. i got fuckin' hitlered.
A solid Prussia strat is to start as the Teutons and ally Sweden and Novgorod(or Muscovy if they are kicking Novgorod's ass) and partition Poland and Lithuania between you and Novgorod. Once you have them fairly integrated, you should have a nice power base and ally structure(Denmark or Hungary helps if you can get them too) to push into Central Europe and defy the HRE.