Put in the work on your endgame and what you already know will dovetail, resulting in solid basis from which to make further progress. That is why Silman grades his endgame material. Apparently Russian chess is learnt from the endgame first and they have a pretty formidable record.
Just my two cents worth.
I realize there are hundreds of these topics, but please bear with me just one more.
My USCF rating is somewhere between 1300-1400. I own 2 chess books. I have a tactics book which I bought ages ago (Didn't even remember I owned it), and I bought the Logical Chess: Move by Move book by Irving Chernev 2-3 months ago. The Logical Chess book made me a considerably better player because previously, I had no knowledge of chess theory.
I'm currently deciding between Silman's Complete Endgame Course and The Improving Chess Thinker by Dan Heisman although I am definetely open to suggestions. My endgame needs alot of work which is why I want Silman's book, but on the other hand, I have heard that Dan Heisman is an excellent chess author for beginners.