It's better to just go for the throat early game.
if the Ukraine hasn't kicked out yet, grab a province or 2 in the first war vs. Lithuania. Not too many to get major AE, but enough *1 to create the Ukraine. The next 2-3 wars will be you forcing Lithuania/Poland to give the Ukraine cores back (no AE, so it's a good 'burn AE' war).
If the Ukraine has a province somewhere (anywhere from Hungary to your border), then take the stab hit and vassal it while you're at war with Lithuania/Poland. It's worth it.
If Ruthenian rebels are wandering around, either the Ukraine or you will get the provinces. Vassal the Ukraine and you get the provinces (though they are usually Ukraine cores, so hand them back ASAP).
It should only take 1 good war to push Lithuania into a Peasants War. Sit back and support various rebels to watch them hand provinces away.
Novgorod is pretty straight forward.
take 100% first war - focus on Finland cores and a path to it. Kick out Finland (to reduce AE)
Novgorod + Tver enter a coalition against you.
Attack Tver
Take ~100% more from Novgorod. they should only have their capital left at this point.
Kazan/etc enter the coalition.
Attack them. Take Novgorod and Tver in the next war. If Kazan, remember the Perm Core.
--- Fail mission to subjugate. Bug in the subjugation code, but you only miss out on a bit of prestige. The free Fabricated claims are still worth taking the mission.
Use Finland to take cores back from Sweden (if they went independent).
keep going...