I went after the dam first, then the coconuts. Seemed to be more of a payoff. You do have to upgrade to the coconut level to be able to farm, but if you start harvesting coconuts, it takes a lot of time for very little food return--time you could be using doing research for more tech points. Fish and gather mushrooms like crazy, upgrade your building first, then build the dam ASAP. Put your fisher on the research table when the algae comes and only upgrade your farming when you absolutely have to (when the dam is built). Don't let your people waste their time gathering 8 points of food per coconut--it takes forever to get any appreciable amount of food. You can harvest 800 food units from your first garden in way less time than it takes to get 200 food units from coconuts. My first 2 villages starved that way. Coconuts seem like the best thing to get after the fish run out, but it's a false economy. Get that dam started instead.
What I meant about teaching people to gather firewood is to use a different person each time the fire runs down low to get firewood to feed it. Someone will eventually start feeding it themselves, but don't devote a lot of time to it. It's just a convenience, and if you just keep a watch, you can rebuild the fire easily. That's another reason to not leave this game run when you're not actively monitoring it (not necessary to watch every second, but just at least able to look in hourly whilst at home doing other stuff).