Try SILMAN'S COMPLETE ENDGAME COURSE,it goes through material section by section based on what he believes a player in each rating class should know.You start out learning the most basic material then advance to the most difficult.
A really good book for learning practical endgame theory!
I find myself losing end games up a pawn, 2, or even 3!
I simply just can't grasp end game principles.Because of this, I research the middle game not only because I love it but I just...fear the end game. I understand nothing and forget simple things. It just doesn't interest me. Maybe someone can suggest something that makes it fun or something. I know not all end games can be fun but sometimes neither can middle games.
Anyone recommend a really good end game book? I prefer it to be big covering beginner, intermediate, and advanced quality. Nothing is too expensive to repair my forever weakness. :(