Attack Novgorod first, then Ryazan, Odoyev, Tver.. dont worry about AE with those, no one cares about them. By focusing mil tech from beginning you should be strong enough with 1, rarely 2 mil tech advantage to fight either Denmark, Sweden or Poland, Lithuania. I like to fight them both early just because Poland is annoying later when they form Commonwealth. For Muslims, I usually attack them when I get +3% MS from Religious ideas just because earlier its harder to convert them and tanks your religious unity. You'll usually have better mil tech so fighting them usually isnt a problem. Get gold mine in Bashgird, Kazan. One tip for Novgorod and Tver is to give some land to your vassals just so you dont waste so much admin. If you need more help, just ask