The way goods trading in Forge of Empires works (in a fair-play scenario), goods at a certain era is traded for half of the count of goods on offer for the following era, and double for goods of the previous era. Read this article to see how much 10 Space Age Asteroid Belt goods can get you if you have patience!
When you hover over most buildings within Forge of Empires, you can see the benefits it provides your city. Nothing new there. What some people may not know, however, is that some buildings form part of a set of buildings, so that, when they are placed alongside each other, you get certain bonuses.
Land area is truly a finite resource in Forge of Empires. Almost everything else can be replenished, but once your expansions are used up, you can't get more land. To alleviate this problem,you need to optimize the benefits you get from each square as much as possible to get the highest yield per square..