Usually I will just lower the tax rate, or even turn it off completely for that specific region. Also, be sure to buy any buildings available in the region, as sometimes the locals are rebelling due to not having the same technologies available as other regions.
when you click on a region capital ( every town has a region capital) click on the name tab that pops up on you UI tab. You'll see some flashing icons on the top left. It can be religious unrest, industrialization, objection to foreign invaders, etc. To cure this keep a garrison of troops, CONVERT THE POPULATION TO YOUR RELIGION( take a priest from your church to that location) and build one of those pleasure gardens. Oh if it's food shortage, build a local fishery or upgrade your farms. You might have to destroy schools or factories =/ which bring in your bling bling.
Also, remember each crushed rebellion counts towards your control in the area. I usually keep a strong garrison to crush rebellions for 5-6 turns. I also do turn one of the towns into a church in case I'm fighting infidels. You can always revert that church into something profitable later on.
I found all new regions hate universities, so as soon as you get all your reseach done, dismantle then and build something else there like a coaching inn or a church and this will bring the population back into hand.
What can be done to stop a Revolution: - Lower the tax or stop taxing the area Effect: Will have limit effect on some areas. If the area have low taxing already, then the bonus from not taxing the area will not be that great.
-> Building or upgrade Theater/Inn Effect: Bout buildings give +x to happiness for all classes, and will always have a great effect. How: Well, some times it can be an idea to break down a building in a town to build up an Inn, but will takes turns to be completed, and the problem can be gone, or moved to a revolution at the time the Inn is finished.
- Converting the people to your religion. Effect: Well, if the ppl in the area already is of your religion then its not much help to convert them. But can have a great effect as Religious Unrest can be a major factor to unhappiness in some areas. How: Well, again it can be an idea to break down a town to build a church if you don't have a priest at hand you can send in. But you face the same challenges as before: It takes time for you to break down the building and build up the church.
- Kick out an unpopular Ministers: Effect: Can have a great effect. The down side is that you can be forced to kick out a minister whit high management skills. So this can maybe be a bad idea from time to time.
-> What to watch out for, before the revolution even starts: Tech: Tech from the Enlightenment tree give the ppl a taste for reformes, and boost the unhappiness in all areas. So here you can plan a bit and try to highter the happiness in the areas before getting the techs from that tech tree.
Enemies: Enemies in the area give unhappiness too. By removing the enemy this unhappiness will be removed and it can maybe restore the order in the town.
Ministers: Your ministers can be the case to unhappiness too, so keep an eye on them and if some of them generate to much unhappiness then it could be an idea to get him kick out.
Religion: Here you can plan ahead too: Analyse the areas you want to capture, if its an area of an other religion then yours then it can be an idea to take steps to ensure you have that one covered. Maybe to move a priest in to the area before you even capture it. If left alone long time enough the converting of the ppl can even give the enemy some problems, and force him to use energy to deal whit the problem.
In the end its al about going through the informations you have about all your areas, and then analyse and find where you must do something before an area get to much unhappiness and move on to a strike and later on maybe even a revolution.