Don't watch the wheel when riding in a paceline, instead look ahead and keep the wheel "in the periphery of your range of vision". Keep the distance to the wheel in front of you steady and never overlap.
Stay concentrated. It's a bit hard when you get tired. That's a somewhat strenuous part of group riding, I find.

Don't slam on the brakes, instead feather them or just coast to slow down - generally do not slow down abruptly.