Rise of the Argonauts

For all these "Earn maximum favor with (insert god's name here)" achievements, the best way is to actually keep all your deeds until you have enough to buy all the favor of one god.

First save your game, then sell your deeds at the Gods shrine inside the Argos or simply pause the game and get to the favors menu. The achievement will pop as soon as you max out the Favor of one god. You can then reload your game and sell your deeds to another god, and do the same for the last 2.

You should have enough deeds once you have cleared 2 of the 3 islands (Kyhtra, Saria and Mycenae) if you get all deeds from those islands.