I started playing this yesterday and I'm having a bit of a problem. I can't seem to expand - my cities are always lacking the funds to invest in science as well. how do i increase my revenues?
Trade with your neighbors, ask them for money per turn for luxuries. Sell your techs.
Also the key to making money in your cities is to Micromanage.
Republic as quickly as possible.
building roads inside your city radius will generate some extra income. Also working on squares that have rivers generates extra. Later on you can build marketplaces and banks.
It was a great game after they patched it a billion times.