The $6 bet is not horrible and not a mistake - it's just a personal preference that I like to slow down with an unimproved top pair as the hand goes along. My usual line when out of position is 2/3 pot on the flop, 1/2 pot on the turn, and if the river is a blank I'll often check to induce a bluff and call most bets. This changes at times depending on the board and my opponent, but that's a very typical play for me.