So first things first, I'm not a coach, but have a basic understanding of the game. Because I go and support my wife during her league games, I was wondering what sort of notes would prove useful, which I could then provide good tactical infomation in between the sets.
You can split coaching into two categories, tactical and mental. Basic tactical coaching: - Take notes on the shots the opponent is using to win, and the 2-3 shots before them that set up the rally, and give advice in order to avoid those situations - Opposite of the above (shots you're using to win, the 2-3 shots that led up to it, and how to re-create those situations) - Look for certain patterns of the opponent (if you high lift, does he always smash/drop? Is he weak coming out of a certain corner? Do they have a favourite shot they keep using? Etc.) Basic mental coaching: - Say anything that improves the self-confidence of your player stay calm/don't be anxious, be prepared to play long rallies/put in hard effort, your defense has been good so keep using it, etc. I noticed that you said "provide good tactical infomation in between the sets." If you aren't allowed to coach at intervals, and only after full games up to 21, my advice would be to give AT MOST 3 pieces of advice. It is better to give them 2-3 important details that they can fully commit to, instead of overwhelming them with information.
It's nothing too serious, they're self umpired and they only really stop a little after 1 game and in between matches to wait for the other pairs to finish. (Sorry shouldn't use sets instead of games...). So there aren't any intervals after 11 points. Good advice for not overwhelming them with information. My wife often complains to me about this.
I'm not a coach either, but I'd chances to coach my kid in her early few years of junior competitions. So, I'd thought about some of these things, and had some observations. Best is to record the games so you two could do postmortem together, and possibly consult a pro. For on court coaching, you'd need to prioritize your possibly many notes (or you could prioritize what to write down). For a player to implement any, advice/reminder needs to be short/simple, and that is within player's ability. Things that require technical/habit changes should wait till later. Best opportunities are stuff she already knows and/or has been practicing (but forget to apply), or situations that happen within the first 1-2 shots. In the latter case, she's the luxury of time to remind herself before a rally begins. E.g. change serve's target areas, or use flick serve, or watch the straight tram line, etc. Anything after a rally begins may become harder (though not impossible); her (or partner's) old habits may take over. Also, pay attention on how you say it - it's advisable to steer away from using negatives. E.g. instead of saying "don't hit too close to the lines", say "hit 6" to 1' away from the lines". The negative words like "don't" would magically disappear, and in her mind the instruction left behind is "hit close to the lines"... Another example, if shuttle seems fast, test it first before game starts. Change to slower one, or tip it. This reminder is relatively easy to implement, as it happened at start of game, after which she doesn't even need to keep in mind any more! If this is not possible, remind her to hit her lifts/clears higher, or play more downward shots. This is easier than to have her adjust her power to shuttle speed. Note, I'm assuming you bring this up because she loses a lot of points hitting out on lifts/clears (re: prioritization). If you notice her tenses up, and couldn't perform at level you think she could (not uncommon), remind her to focus on performance goal rather than outcome goal. Presumably this is not be-all-end-all games. If it's lost, she could join another one, and then another one. So, refocus her mind on using her skills as a goal is better than focusing on winning. This is also a way to focus her mind. Practical advice such as slow/deep breathing before start of each rally could help relax muscles (instead of just telling her to relax; then you're focusing her on her tensions). Remind her to warm up (sweating but not tired) before games would also be good. If she's playing doubles, there's also the question/element of coordination with her partner. Again stay on something within their ability to adapt.
During a game I prefer just one simple idea. Like at the last competition at the 11-point break a friend said "faster, Smash more." and that was great advice and something I could stick in my head. If someone tries to tell me tactics and anything more than 5 words long, forget it. It clouds me too much and makes me "think" too much. So I advise just one simple thought or idea. Could be tactics, like "his backhand is weak" or could be mental like "take a deep breath, relax." But in the middle of a competition a shorter, simpler idea is better.
Some great replies already. I am a trainer and coach, so just to reiterate: Yes, one or two tactical items max. Mental coaching is often just as important (focus on your own playing, etc. but best tip: just have fun! Immediate 50% increase). And keep it simple.
