The easiest way to make money is by mining gold and having a palace.
Second-best is to produce raw materials(e.g. reeds) and convert them into goods(papyrus) which you export.
Third-best is to import raw materials and to convert them to goods for export.
Fourth-best is to produce and export raw materials.
As a general rule, sea trade is less efficient than land trade. For a big sea-based export industry you will need multiple docks with nearby storage.
You will also make money from taxes, but it will never be sufficient unless you are making luxury housing.
When you start a new city, analyze the trade situation and pick a couple of industries. For example, in Abydos you can produce papyrus from reeds, linen from flax, and beer from barley. In the first year you want to get one of these going, quickly followed by the others. Pick a site for the industry and BEFORE YOU DO ANYTHING ELSE, build there a road, a 2x2 square of houses, a firehouse, and an architect. If near the river, build an apothecary too. Open the export trade route that you will need. Leave space for the industrial buildings.
Now set up your main housing somewher else on the map. As your population grows, build first the raw materials (reeds) gatherer, then the industry (papyrus maker) then a couple of dedicated storage facilities set to handle only reeds and papyrus, then (if necessary) a shipwright and dock. But don't build things until you have enough workers!
Watch your industry and fine-tune it so that it produces all that you can export. If raw materials accumulate, buid another factory. If factories are idle, gather more raw materials. If export goods accumulate, you may need a second dock. Once the industry is established it will generate lots of money with little effort on your part.
And NEVER let your city slip into emigration through high unemployment. If people leave those first four houses, the entire industry will shut down.