Your food settings should always be set to minimum i.e. 2 (where possible), though depending on game needs you sometimes may have to focus more on production or Science.
I generally leave my food for as much growth as possible. Some improvements, temple, Theatre etc will help you out max your Empire sliders for growth etc by reducing unhappiness, as will wonders such as Ramanyana. Farms also help empire growth.
The AI players always grow or start better in games as the AI has an advantage (programming), depending on the dificulty setting you are at will also determine how fast your empire grows. So if you play at impossible you will notice its harder as more people are unhappy.
For more details (as there are lots of tips) have a look through some of the CTP2 threads especially the FAQ and Strategy ones.
When youve learnt a bit more try playing some multiplayers games. If you want a game email me at
Bart_975@hotmail.com