Find maxmin in non zero sum games

I can’t figure out how, in a general-sum game, you can find the maxmin for a player. In some games it is trivial (e.g. player 2 chooses the pure strategy L that no matter what player 1 chooses it will always lead to a worse payout that R for player 1). But for some it is not and I can’t find anywhere how you can do it.