IF THE GAME CRASHES AT LAUNCH
After installing the GoT mod, right click CK2, hit properties, find the Betas tab, and turn it into the Beta version by selection a version. Now the game should launch without crashing.

MANDATORY THING TO DO
Go to options and switch off autosave. (or the game will crash with each autosave)

SUPPOSEDLY MANDATORY THINGS TO DO
Don't flick through the portraits and lands and so forth, or the game will crash when you play, find a suitable candidate, restart the game and select it in one try.

After each second save, restart the game before you continue, because if you try to save a third time the game will crash.

Don't zoom in/out and speed up/down at the same time or the game will crash.

Additionally it is suggested to keep the strain on your hardware low, disable water animation (which serves no real purpose gameplay wise) and turning off the tree rendering, to keep your RAM free for other programs. It also might help to keep save compression off if you are getting corrupted loads.

NOTE
This is my personal experience, it might not work for you or it might so, I'm just trying to help.

Check out my other guides/mods

http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=354306878