Just got Cossacks and am lost. Please ELI5 estates.

Hi all, I just got the Cossacks DLC, and I'm lost. I already read the EU4 wiki on it, so I understand the possible benefits/drawbacks of each estate, but I'm not exactly sure how I should be managing them or what I should be doing.

I'm not exactly a total noob, I have about 300 hours in game and have managed each new expansion I've added just fine, but I feel like I'm missing the "bigger picture" or "long view" of what estates can/should be doing. Cossacks was always mentioned as a "must have" DLC, so I feel like I'm missing something.

Any and all help is greatly appreciated.