It goes without saying that every ensemble member should keep their eyes on the conductor(not a hard steady stare, but flicking eyes back and forth between the music and the podium). I notice in flute ensemble rehearsals that a lot of flutists forget some of the basic skills of good ensemble. Every member of the group absolutely should memorize the first notes and last notes of a work and look up during those key moments! Those notes will not change even if you stare them down, so look up. Also, open your ears and listen across the group for a sense of exactly how the release will be executed. Other places to look up that are mandatory are during tempo changes, meter changes, or during rests (such as typical Classical era V-I cadence passages). Members sitting closer to the front or at mid range can keep a good visual on the conductor in their peripheral vision, but members near the back really must look forward often. It takes practice doing this so that you are confident your eyes will return to the page at the proper place after looking up, so use your rehearsals to practice this skill as well as working on all the other elements of your music.
Here's to productive ensemble rehearsals!