Rooks/pawns

I am ashamed to admit my deficiency in endgame ability. My prowess lies in the opening and middlegame, and my victories often stem from aggressive play leading to tactical wins or checkmates. However, I realize that it is terribly inefficient to rely on such fireworks every single game.

In fact, today I lost a casual game to a friend at the seam between middlegame and endgame. I was two pawns up, and had a knight/bishop against two knights. At one point, I had the opportunity to reduce our queen/rook/rook trios each to a single rook. I lacked the confidence to follow through with the exchange, since I was uncertain of how the endgame was to be won. Worse, I lost due to a humiliatingly simple mate since I was too focused on attacking with my remaining the pieces.

In short, I desperately need to learn endgames. I find it a bit humorous, but I believe I am ok with basic bishop vs. knight endgames, but have trouble with kings, pawns, and rooks. I don't think I have trouble with either the Lucena or Philador positions. Problems arise when my fear of king safety delays my king's advance towards the center. Perhaps I overlook something simple, but I find it quite difficult to simultaneously protect all pawns with king and rook AND get my king centralized.

All advice appreciated! (general tips, books to study, youtube videos to watch, etc.)