basically you want to only play out of position with really strong hands, AND as the aggressor.

The problem with being out of position is that any bet or raise you make shows extreme strength, and any check you make shows extreme weakness. Decent players in position use these cues to efficiently read your hand.

You counter this by sometimes checking good hands and bluffing weak ones, but generally you'd rather be in position, where your actions do much much less to reveal your cards.