CK2... that's easy. Have lots of kids, murder your siblings, and declare war on France.

As far as AGEOD games go, that's where they shine. Since they're WEGO turn based, it's easy to sit back and analyze things without feeling rushed or tempted to jump the gun. UI options are also limited but useful enough to allow you to focus more on strategy than logistics and tricky game interfaces.
Have any more specific questions, feel free to ask. There's tons of gamers here that know their stuff.