I find a lot of starts I get are forest-heavy with grasslands or plains underneath with few (if any) hills, and of course once I chop those forests their production (and health) turns into the commerce/food of a cottage/farm. Your problem could be cutting down too many trees in the fat cross of the capital, if you're chopping for a wonder or a settler or something else important, you might want to chop a forest outside the fat cross but close enough so that the hammers won't go to another city. That's not always feasible, however. I would say keep the forest tiles you're able to work in the fat cross for a while in the early game until you have a good production city set up, then you can start replacing them with whatever it is you need. I usually start by chopping the ones by rivers and putting cottages there for the extra commerce. Speaking of rivers, many starts are also river-heavy, and once you unlock watermills you can turn your capital into a powerhouse that way if you wish.