My first and only city, been paying one year now. I ‘camped’ in EMA to get used to the game and raise a few GB. I also lingered in FE as it is a very enjoyable age. Almost decided to stay there, but my first city so I felt I should experience all the game has to offer. If I decide to create another city, perhaps I will end up camping permanent in an age. I have been in AF for about a week now.
I found I really did not lack for any resources as I aged up. Yes, each age gets more expensive, but if you upgrade buildings they produce that much more and you also have more room to produce resources in. It is actually kind of a wash. It costs more but you produce more and it evens out to be able the same cost.
I only traded up enough in goods to get to a needed research task. I do not remember what most were; FE was to open Hoovers and AF was to open up the harbor. Then, I make whatever else I need to do research in that age and have a little extra, then age up. I really had no trouble battling in each age even though I was at the very low end of the attack/defense that everyone posts is “needed” before aging up. No, I could not auto to 75 attrition, but I was always in the group right behind the 1000 attack folks and was able to do GE 64 in each age. Yes, I needed to do some negotiating, but I made plenty of goods for it.