do you build all your cities on grassland or plains?.
Yes if possible. I always avoid rocky zones. My cities have quite all pop 20, but I don't use a default pattern to build them, even if I don't overlap.
do you know when or how to use the Hanging Garden.
sure, at the end or before biology, when all my cities can support it with extra tiles already worked
do you know how to balance your economy.
What do you mean?
do you know how to use cottages?
I think....
But maybe my mistake is here: I hate to make farms on theme.....
and your tech tree??
food --> slingshot to CS and early religion---> masonry for Pyramids ---> literature for GL ---> Guilds (1st golden age) ---> Nationalism ( 2nd GA) ---> military tradition for fast conquest (about 500 AD) --> liberalism, economy, biology, communism, phisic (usually 3rd GA), corporations (1000-1100 AD) and game over.
On large maps I build UN and win by "bulgarian"
elections in 1000 AD (on marathon)