unrelentingly aggressive: the right way to play heads up?

[blaze666]

iv'e heard that the best way to play heads up is unrelentingly aggressively. could someone explain this in more detail,
what if you are played back at?
when should you stop?
what about your image?
how much to raise?
should you continue with aggression if you are called?
what if you hit the flop?
should you pick your spots well, or go in with guns blazing?