At levels monarch and below, you have 2 good choices for building monster economies ...
1. The Bureaucracy cottaged capital. Make sure to get an early great scientist for an academy in the capital. Have the capital build as many cottages as possible. When you can build Oxford University in the capital. After worker techs, beeline to Civil Service for Bureaucracy capital bonus.
2. Settled specialist super science city. For specialist economies, run lots of scientist specialists and settle them in your highest food city. This city should always run as many science specialists as possible (unless growing, or needing production). Your super science city will have an academy, all your settled scientists, and oxford. Ideally, get the Pyramids and run Representation early. Can be as good or better than 1.