Have a reduced option of troops in order not to overwell initial player but also a tier system, just like mount & blade, like horseman, infantry and archers, but you can level up your horseman up to knights, your archers up to sharpshooters, and your pesants up to infantymen.
Have a happiness system were the more stable your lands are in terms of food supply, water supply and confort like enough housing will permit you to rise your taxes to a higher persantage. And please have a preview of the results in the sreen in so that the player can make informed decisions so that we don´t have to guess what will be the results, exemple have the screen show that in we rase the taxes to a specific level "this will be the happiness level" that the population will have, or this troop consumes "x" amount of food and right now you produce "y" amount of food and you have "z" amout of food left.