Advice sought- close game

[Hendrik]

This was a game on Sahara, I picked random and drew Nubians, my opponent was French. There is some raiding action by me as soon as I go classical, the French player follows up with some raids of his own, but neither side does a lot of damage. He is the first one to attack with a big force in gunpowder but he has no HI and is repelled by my calv... the game is decided when he takes one of my cities in the Enlightenment age.

I would think that as a Nubian, my economy should have been better than his. Any expert advice about how I could improve my economy would be appreciated. Those French supply wagons ended up costing me the game.