Population Hint

When you take a small town off the hands of your enemy.Dont start boosting alot of units/buildings in there.
Instead try this on for size, build the lowest units (works best with peasents).
And build alot of them then when you have as much people you want move the peasents unit in the towns where you need population then disolve the units and the peasents will become loyal romans works like a charm:egypt:

another one:
exterminate minor cities and up (or enslave if you want but not reccomended)
occupy large towns and smaller.