To keep them from starving to death, I do the second level of farming first, then I do second level of spirituality (because it's the next cheapest), then second level science to try and get tech points faster, then second level construction, and if I haven't gotten alternative ways to increase my medicine tech points I go for second level medicine (though this new game I started I was lucky and got second level medicine thanks to an Island event), then maybe I'll go for second level fertility if I feel it's necessary. After that, I go for third level of whatever's cheapest (farming usually, then construction, then spirituality, then fertility). This time around though, I'm not going to max out science right away. I learned the mistake of doing that in the last game.

Now, maybe it's just this particular game, but, I've noticed that by doing it the way I just listed, my villagers are seeming to learn things faster, and I'm solving puzzles more quickly then I did the last game.

I mean, I still had about 600 berries left on the berry bush, and I managed to buy level two farming, and get them started on alternative food forms, and save the berry bush from being depleted like in my first game.