by various creators
The endgame is the final stage of the game when the life & death status of all big groups has been determined and the remaining moves aim at expansion of own territory and reduction of the territory of the opponent. It would be an exaggeration to say that most games are decided in the endgame, but if the players come out of the middle game without any big advantages, the winner is the player with the better endgame skills.
One important skill in the endgame is the ability to calculate the value of a move. Since you will, in general, want to play bigger moves before smaller ones, being able to determine the size of various moves will go a long way toward increasing your endgame strength. The other important endgame skill is knowing the basic endgame tesujis. Afer working through the 200 endgame tesuji problems in this collection, I have no doubt that you will look at the endgame quite differently.
For each problem, find the best move. Consider the value of a move and Sente/Gote relationships. Kos are big in the endgame.