You are right that there is no really simple book out there that deals with this "get better at technique" phase as most really strong players (who author those books!) probably don't get that this is a"struggle" for the club player.
Practically speaking, I've always felt that squeezing out the draw (or playing actively for winning chances) is really a matter of keeping your move-quality consistent and clean and not being the guy who loses his focus and blunders or miss a tactical shot.
This is probably why players who are very strong tactically don't often have to worry about technique during club play... statistically, their opponent is going to miss a shot before they are!
Two exercises to train this are:
a) Play won-game positions against computers at max. difficulty at a suitable time control (15 mins each side)
b) Play drawn-game positions against computers at max. difficulty
Depending on where you are at, I'd start with basic Won and Drawn games (occuring both in KP vs K) and move upwards in progression (more pawns, more pieces etc.) until you reach a position like the one above.
It's really a lot of work (I'm still struggling with trivial rook endings vs computers) but what stronger players in clubs have taught me is that good technique is NOT "getting it right some of the time" but "getting it right ALL of the time". If I wake you up in the middle of the night and ask you to the hold the draw above against a 2500+ engine, you really shouldn't blink and have enough practice under your belt to perform on demand!
There seems to be a phase in many of my games when mate threats are off the table for the most part, and we're headed toward the endgame. By endgame I'm talking about basic endgames with many pawn exchanges and few pieces on the board (e.g. K+P, K+R+P, etc.), stuff that you learn in "endgame books". I'm having trouble with this in-between phase because both I and my opponent have so much more mobility for our pieces, and calculating is difficult. Check out this position:
The queens have just been exchanged and both players are fighting for the endgame. Engines say this position is close enough for a draw. But getting the draw is a matter of whittling down pieces and pawns for both sides until you reach a much simpler end-game, so-called "technique". Meanwhile each side has a myriad of tactical possibilities thanks to an open board and very mobile pieces. As far as I know, there is no literature out there that teaches this "technique", which I've recently heard called "liquidation".
The three traditional phases of the game seem to have their general principles which help guide beginner players like me to find reasonable plans. But as for this "in-between" phase, it seems general middlegame principles (e.g. create open lines for your pieces while restricting your opponent's pieces) no longer apply, and general endgame principles (e.g. active king) don't apply yet. Can anyone point out or point to something that will help me learn how to better play this phase of the game?