washedUOB,
Just like any ball game or sport, the critical separation is ball control. As long as you have ball control, and the longer you keep it, the less chance, logically for your opponent to mis-hit or slop the ball. An early thing I learned early is how to fight for, and I mean REALLY SCRAP, to get control of EVERY LOOSE BALL, no matter if it's a tour event, a regional, a local or just pickups. Learn to fetch that loose ball anytime and anywhere, ASAP. This part is where the good singles and all-around players separate from the doubles and specialists players. You may or may not be better than your opponent/s, but you can definitely try to live with the ball, getting the most attempts and minimizing the other's chances.
Verbal gamesmanship? I say internalize it, speaking silently or even aloud to yourself, to keep that sence of urgency about always getting that loose ball. Tell yourself that the opponent/s will get the breaks, perhaps all of them, and when you can convince yourself to accept that, you won't mind or whine or change your demeanor when they do happen, but simply continue on, grabbing control of the majority of possessions. If breaks don't happen, or stop going their way, then your mantra is working even better! This is also great when reinforcing your game through practicing to have smooth passing with 2-3 identical looking options per series. Same goes without saying for shooting, to get a higher percentage and keep pressure on the opponent/s. Keep on talking, to yourself. If you won't listen to you, then noone else, least of all the foosgods, will.
Tempo is another great characteristic of advanced play. Simply playing slower will backfire if the opponent gets even more comfortable with that particular game, and remember they've already got the breaks, prolly pulling even or even pulling ahead with no real effort on their part. Playing slowdown or keepaway after you've surrendered the lead can be really SILLY, sometimes. What works better is what I train those noobs here locally to do, especially when they're playing nets. I call it "Pulling the String." Decide to clear, shoot, or pass a ball quickly, immediately or within 2-3 seconds when the opponent/s seem to be slowplaying. If they're excited, flustered or passing and shooting quickly, THEN grind them down with a slowdown, only clearing, shooting or passing after 14 seconds. And also throw in a few shots/passes at the 7-8 second midpoint of possessions. Most good opponents will be able to "time" you or your partner's rhythm if you simply maintain your normal natural passing and shooting cadence. "Pulling the String" keeps you aware of the game's tempo, and MORE IMPORTANTLY, prevents you and your partner from being sucked up yourselves into certain passes or shots the opponents can anticipate, block and steal.
"Pull the String" a few times, especially with familiar players from your group, and you can do what almost every goalkeeper in a tight competitive match MUST learn to do, unless they can block like Jesus and brick the Devil himself. In doubles, it is easiest for the goalkeeper to control the tempo by "Pulling the String," with the forward more easily following the goalkeeper's cue. This prevents the opponent/s from settling down and grooving into the game, and adds release point timing as another factor to worry about in defense.
There will always be streaks within a game where the ball is moving and changing possessions very quickly, and portions where every touch of the ball is very deliberate. "Pulling the String" and breaking up or at least harrassing the opponents away from getting into a groove or zone should always be part of good advanced play.