How can an Elo 1300 player improve his or her endgame? I have noticed that, among opponents of Elo strength about 1300 (USCF class C to D), many play the opening and midgame almost as well as a 1400- to 1500-strong player but seem suddenly to drop to, say, 1100 strength as the endgame approaches. The 1300-strong player who blunders away endgame after endgame is a familiar character in the world of chess.

Without an excessive investment of the player's time, what are some ways a typical 1300-strong player can improve his or her endgame?
Some advices:


Look at grandmasters' endgames with comments. 


Replay their games and try to understand their moves and the evaluation of commentators. There are several good books, I think Evgenny Shereshevsky's excellent classic "Strategy in the Endgame" is understandable at 1300-level. At least most of it, and you can keep the most difficult examples for later when you will have developed a better understanding of general principles. Some books about Bobby Fischer's endgames have been well commented too. I suppose there are good videos/DVDs on the market as well. Avoid anything overly complicated right now, like John Nunn's works; Mark Dvoretsky's and Karsten Muller's ones are very good but too hard at 1300 elo - keep them for later.


Start with pawn endgames. 


The rules there are somewhat more clear-cut (there is basically one single goal: queening one of your pawns first), and they are mandatory if you want to understand more complex endgames later on, because several concepts are similar and because they may transpose to pawn endgames in case of exchanges.


Do not try to swallow too much theory. 


Endgame theory can be surprisingly complex, it is a dry matter to memorize, and pratical endgames is what you should be looking for. At 1300 elo, I assume you already master the basic mates KQK, KRK and KBBK. KBNK is fun to look at but not super useful in practice, learn it if you enjoy it but don't force yourself if you don't.

I would still encourage you to learn KPK well enough to be able to evaluate any position with KPK in less than thirty seconds, and be sure about the next best move. Have a look at KPKP theory (counting in pawn races, opposition, trebuchet) and at KRPKR (Philidor, Lucena), but already here you merely want to get familiar with the ideas, not to remember everything.


Some training websites 


like chesstempo or lichess offer endgame exercices and adapt their difficulty to your performances in solving them. If you have fun doing some once in a while (I sure do), do it! Usually the free registration is enough to get access to five or ten exercices per day - just the right amount for effective training !


Stay away from tablebases (and more generally from chess engines). 


You may use them to have a look at the evaluation of a given position if you have already studied it by yourself or with a book/video and want to check your conclusions. But going through variations generated by tablebases is disheartening enough : sometimes they lack logic, or make you feel that simple things are overly complicated because they try to minimize distance to mate, and they come without explanations (or explanations limited to even more complicated variations)... 


If you play endgames in your own games, study them afterwards. 


The best way is: first alone or with your opponent, then write down your main conclusions/interrogations, and then review the endgame with a stronger player / a coach / a reference book if the position is a theoretical one / a software if really you have nothing better available. Finally, compare with your first notes, that's when you will make huge progress about your thinking process !

Good luck !