"Do unto others as you would have them do unto you." is a kind of a planning-ahead strategy if you believe that others are going to use "tit for tat". Maybe?
And besides, I'm talking about a strategy that is beneficial to the group (and to group members indirectly thereby. Not a strategy that is most beneficial on average to the individual at each encounter.
Actually, the successful game theory strategy is "tit for tat"
which would be quivalent to: "an eye for an eye"