I am new to EB

[Parallel Pain]

From what I can tell it is unrealistic at the start of the game to try to always have something building in every settlement and have 4 units of garrison in each town.

I usually put one-non general unit as garrison in each town, and then put just enough troops in some armies to defend my border and barely attack. Even then I don't have enough money to build something in every settlement every turn. So usually one or two cities build units, while everyone else goes port, roads, mines, and markets. And I also have to wait and safe up money to build expensive mines.

The down side of this is if one of my armies are destroyed in battle and the AI have sent enough troops from different directions to exploit its destruction, I could loose half my empire before I could recover, or really the whole empire.
But that's really the best way to do it anyhow.

Of course I was playing on Saka Rauka VH/VH so it's not like I had a choice.

For the start usually you have two choices: disband or attack
Attack and attack until you're back in positives. Or for diband, attack a few settlements, and then disband your units and build up your economy.