Things happen quickly in EotS, and there are a fairly large number of commands that you can give. It helps if your team has a clear message code that everyone follows. You will develop your own, but here are some common terms.
Towers: BE, MT, FRR, DR
Incoming: inc MT 2 ... two incoming to Mage Tower ("inc MT lots" basically says "too many to count")
G3 cap FF ... group 3 please go cap Fel Reaver Ruins
G1 get mid ... group 1 please go get control of the flag area
CAP CAP CAP ... what are you doing, you idiot, cap the flag!
... and so on.
Distraction Versus Discipline
Because of the way EotS is set up, it is almost impossible to go very far without meeting someone from the opposite side. The result is that spontaneous fights tend to start up all over the place. Sometimes your teams will need to avoid a fight so that they can get to where they need to be. You may have to keep reminding them of this.
EotS has a lot of narrow passages where crowd control is very effective. If you need to leave, CC and run.
Go for kills. Don't just battle, look for the opponents who have the lowest health and focus fire on them. GYs are far enough from fights, that rezzers may not make it back before the fight ends.
If a team has a well protected healer and you need to be somewhere else, then just go. In the time it takes to kill the healer, you could fail at your main objective.
Capping Towers
The towers cap over time depending on who has the most people standing on the site. This is worth repeating over and over again ... if you're not standing on the hill, you're not helping to cap.
If everyone leaves before the "capping" needle gets all the way over to your side, it will stop moving.
Everyone absolutely MUST fight on the hill.
When you cap a tower, make sure at least one person stays there until the meter is maxed out for your side. This makes it harder for the other side to take the tower back.
Capping the Flag
Points for a flag cap depend on the number of towers you control: 75, 85, 100, 500 points.
If have the flag, AND you control the center, then it is best to cap the flag, even if you only have one tower. Two caps with one tower are worth 150 points. Waiting until you cap a second tower only gets you to 85.
If you have the flag and the OTHER TEAM controls the center, then do not cap unless you hold three towers. With two towers, you are just taking 85 points and giving them the flag. With three towers you are taking 100 and giving them a flag worth only 75.