Secretiveness among members needs to be discouraged. If there's an offsite meeting or finding, the results need to be shared with those who could not be present. It's such bad form to have suspicion coloring what's done. It leads to mistrust and eventual exits that create delays in the project while the replacements are hired. And the project will then have to absorb at least some of the replacement costs of search, intake, training, and returning to the point where the team was before the loss of manpower.
Make certain systems work. If there's a malfunction, the basis for it needs to be discovered and disclosed so that it won't happen again and so that successors don't have to deal with it. The basis for the malfunction, once discovered, needs to be revealed so it can be avoided and personnel can feel as though their efforts are subject to being thwarted (i.e., a major waste of time).
If someone on the team is promised feedback, more information, asked to attend a meeting, they need to receive what they've committed to. Make it on time, or as close to on time as possible. They may be sitting on something that requires that bit of information; delay causes their part to either not be delivered or delivered late. Coming back to the team member for a meeting that's before the appointed time is the same as telling them their schedule has no value and that you feel they're simply sitting around with nothing to do and waiting for your precious presence. Don't come off as smug and self important.
Additionally, the team member may have quite a bit on their plate. Putting the meeting (whether in person, by phone or Skype, or some other mode) on their calendar and clearing out a point when they can give you their undivided attention allows them to keep their workflow moving and timely. A spontaneous change because one has jumped the gun or suddenly has an open slot in the day is quite simply selfish. Other priorities then get shifted to a different situation. Progress is thrown off to the point of having to be rescheduled to another day or may even be lost because there simply is no longer any time for the exercise. Keep appointments. If it can't be done and you realize it, reschedule for another time that is mutually convenient.
Now that we're in the 21st Century, people seem to forget some of the Web 1.0 netiquette we used to practice. There used to be these cute little abbreviations and initials that gave us clues, initials such as "afk" which stood for "away from keyboard" (a tactful way of saying I need to get something, put out the fire, go to the bathroom, etc.) and "brb" which stood for "be right back." Both of those let us know that the person on the other end was no longer available for a short duration.
Unfortunately, we've lost touch with those practices. Now people will walk away from the computer and have a meal, go visit with someone in another building, have a conversation with someone else in person for 30 - 60 minutes. Respect your team mates and their time. Let them know when you're stepping away. Let them know when the absence will be protracted. You're more apt to get their future cooperation when they're shown that they and their time are valued.