strijder20
Wallowing in irony
I've finally managed to win a domination win on RFC-DoC without collapsing 
I took Rome, which seemed a decent choice : they have an average amount of Core/historical and lots of contested area to expand into. They also don't spawn too late, giving you a decent amount of time to prepare your war machine.
I took out Greece - which is an obvious thing to do - ,founded Rome, Pompei, a city on the PH hill NW of Constaninople and a city some tiles south from Vienna.
I did the usual wonderspam, and with Greece dead, managed to get most of the classical wonders. Then I just defended against the barbarians, prepared some legions and catapults and waited for the Euro-civs to spawn.
Germany (Austria) started at war with me, so I took them out, and kept Frankfurt (Bona Mansio).
Spain peacevassaled to me! I love how Spain, France and Germany have the tendency to vassal themselves out to Rome
I then had major stability trouble, probably because I conquered Germany, so I moved all my armies to my capital. After the inevitable collapse I took most of them back. A few turns later, my stability rating was very solid
.
Portugal declared for me for whatever reason, so I took Lisbon. They hadn't founded Ponta Delgada yet, so it finished them off.
After this the Turks attacked me. One thing I'd like to say about warfare in RFC is that you shouldn't start wars yourself : neighbours are bound to declare at you once, and declaring yourself may lead to a dogpile. I took Angora, Tyrus and Jeruzalem and peacevassaled them. Their vassal, Persia, was still at war with me, so I took Tehran and Persepolis.
By 1700, I had rifling (I had a somewhat mediocre tech rate, but I beelined it) and I moved my troops to the border of Prussia, preparing to take Frankfurt back once their spawn period was over (1730). But the cowards became a protectorate of Russia! I bravely ignored the Russian bear, declared anyway, took my cities back, and conquered Eastern Europe, capitulating the Russians. It was around that time that Britain peacevassaled to me.
Egypt collapsed, so I conquered the independents down there, leaving me about 5 % short of Domination. So I had to fight one final war. I declared war on the Unstable/Collapsing Mughals, who promptly collapsed (thank you very much). I won after conquering India and some cities in Thailand from Mongolia (Mongolia was incredibly stable - it was 1900 AD - and already had Machine guns).
One turn before victory. As you see, I don't control terribly much land myself - my vassals had about double the amount of land I had.
Could be better, but could also be worse - I finished this game quite late.
I experienced major stability trouble (at the end, I was unstable in a golden age). Could anyone of you here who has more experience with domination give some hints on how to improve your stability after conquest or in general? What civics should I use? In this game, I went Autocracy-Imperialism-Representation-Free Market-Patriarchate. Should I have gone for Totalitarianism if the game lasted longer?
Should I have razed more cities? Liberated more cities?
I think vassals are key in domination. But were my vassal choices the right ones? Especially about England I have doubts.
Thank you in advance.

I took Rome, which seemed a decent choice : they have an average amount of Core/historical and lots of contested area to expand into. They also don't spawn too late, giving you a decent amount of time to prepare your war machine.
I took out Greece - which is an obvious thing to do - ,founded Rome, Pompei, a city on the PH hill NW of Constaninople and a city some tiles south from Vienna.
I did the usual wonderspam, and with Greece dead, managed to get most of the classical wonders. Then I just defended against the barbarians, prepared some legions and catapults and waited for the Euro-civs to spawn.
Germany (Austria) started at war with me, so I took them out, and kept Frankfurt (Bona Mansio).
Spain peacevassaled to me! I love how Spain, France and Germany have the tendency to vassal themselves out to Rome

I then had major stability trouble, probably because I conquered Germany, so I moved all my armies to my capital. After the inevitable collapse I took most of them back. A few turns later, my stability rating was very solid

Portugal declared for me for whatever reason, so I took Lisbon. They hadn't founded Ponta Delgada yet, so it finished them off.
After this the Turks attacked me. One thing I'd like to say about warfare in RFC is that you shouldn't start wars yourself : neighbours are bound to declare at you once, and declaring yourself may lead to a dogpile. I took Angora, Tyrus and Jeruzalem and peacevassaled them. Their vassal, Persia, was still at war with me, so I took Tehran and Persepolis.
By 1700, I had rifling (I had a somewhat mediocre tech rate, but I beelined it) and I moved my troops to the border of Prussia, preparing to take Frankfurt back once their spawn period was over (1730). But the cowards became a protectorate of Russia! I bravely ignored the Russian bear, declared anyway, took my cities back, and conquered Eastern Europe, capitulating the Russians. It was around that time that Britain peacevassaled to me.
Egypt collapsed, so I conquered the independents down there, leaving me about 5 % short of Domination. So I had to fight one final war. I declared war on the Unstable/Collapsing Mughals, who promptly collapsed (thank you very much). I won after conquering India and some cities in Thailand from Mongolia (Mongolia was incredibly stable - it was 1900 AD - and already had Machine guns).

One turn before victory. As you see, I don't control terribly much land myself - my vassals had about double the amount of land I had.
Spoiler :

Could be better, but could also be worse - I finished this game quite late.
I experienced major stability trouble (at the end, I was unstable in a golden age). Could anyone of you here who has more experience with domination give some hints on how to improve your stability after conquest or in general? What civics should I use? In this game, I went Autocracy-Imperialism-Representation-Free Market-Patriarchate. Should I have gone for Totalitarianism if the game lasted longer?
Should I have razed more cities? Liberated more cities?
I think vassals are key in domination. But were my vassal choices the right ones? Especially about England I have doubts.
Thank you in advance.