Volstag,
You have two problems going on simultaneously in your games if cities are falling into disorder.
First, use the governor to manage citizen modos until you get a better handle on things. There is some inefficiency loos in some cases, but you can set wether to emphasize food or production and that will prioritize some things in the cities. One turn of disorder will negate 10 or 20 turns of micromanagement benefit, so avoiding disorder is more important than squeezing one extra sheild. (note that I squeeze lots of shields, grain, and gold but also micromanage to avoid disorder when I do this.
Second, if your cities are growing above size 6 in the early game, then this is usually an indicator that you are not building the righ things and the right unit sequences. Food cost to grow a population point doubles after size 6, so you really want to build all the settlers and workers that you possible can before taking the cities up to the next size level. This really is a key game skil so work to mater it.
I will usually try to pick one city fairly early to max out its sheeld production by any means possible. If this means more people then so be it. Otehrwise mycities oscillate between 3 and 6 people while I crank out settlers, settlers, settlers, and workers, workers, workers (mix in military units and improvements in between to balance things out.)
As a side note, disorder and unhappiness may also be related to knowing how to use military police powers properly, I am amazed at the number of new players that stand warriors in the fields next to their towns without grasping that the military police unit will make one person happy in the town and this will increase your score by at least 1 point per turn plus potentially increase shields, food, and gold whne more people can work effectively.
Good luck,