Stop talking so much. Seriously. Stop talking so much. If you are talking, the ensemble is not rehearsing. I once played for a conductor who was perplexed that the ensemble was not learning music very quickly. The conductor said to me, "I don't understand why they can't learn this. We rehearsed this for an hour." I thought back to the rehearsal. The first 15 minutes were spent "warming up." Of the remaining 45 minutes, about 20 minutes were spent stopping the group to explain something. In the conductors mind, they had practiced for an hour. In real life, the group had only worked on the piece for 15 minutes.
When you talk, it must be absolutely efficient. This is especially important because you don't know what will actually work. Sometimes you try something, and the ensemble doesn't respond to it, so you have to try something else. The more you can get them to respond to physical gestures without needing to talk, the more time you will have to practice.
Above all. NEVER SHOUT INSTRUCTIONS TO THE GROUP WHILE THEY ARE PLAYING AND SINGING. I am so weary of conductors shouting things while the group is rehearsing. There are so many things wrong with this. Let me give you a few.
1. If they are listening to you yelling, they are not listening to each other.
2. You are making a tacit acknowledgment that your physical gesture is not communicative.
3. You are elevating spoken communication over non-verbal communication (a weird thing in a musical context).
4. You are saying that what they are communicating musically is not as important as what you have to shout over them.
5. It's rude to interrupt people while they are doing something expressive.
6. People don't like to be yelled at and usually don't entrust themselves to you for musically expressive performing afterward.
7. They can't really pay attention and listen to you if they are doing what they are supposed to be doing, so once again you are wasting rehearsal time.