This is one of my favourite games of all time, if played with the retrofit mod, which resolves some important issues. I love playing as France -> if you capture all the rebel settlements in your immediate area, you'll quickly become the biggest faction. Then, you launch an early crusade to gain Papal favour et voila, you have a nice amount of land you can take without the Pope getting stupid about it. Just keep in mind you need a lot of priests for conversion, and pilgrims to make up the numbers so you can use them as town guards. You can also move your capital closer to help keep public order. Egypt should fall quickly enough when you move fast. Basically what you do is you concentrate most of your resources on capturing the Holy Land (you can launch more crusades to get big armies there fast), and when a faction gets excommunicated in Europe (and trust me, they will), you destroy them as quickly as you can (but keep in mind not to kill their faction leader). If you train a lot of priests, you will have a lot of cardinals so that when the Pope dies he'll always be a French pope, who is enormously biased towards you. When you have full Papal favour you can even ignore his threats a couple of times without getting excommunicated (you only lose a bit of favour). It's also important to ally with the Papal states early on.
My favourite part of the game is defending your Eastern territories against the Mongols and the Timurid invaders.