What have the biggest impact to the spectators? (in a coins across routine)
1. To tell what is going to happend, and then do it!
2. Or The say what just had happened?
Usually you shouldn't tell what is going to happen to the spectators doing any magic trick, but there are some circumstances where this strenghthens the trick. You just have to experiment.
Saying what has just happened is basically stating the obvious for the spectators. They just saw what happened...so they don't have to hear it. However, you can say something like "So, that's one coin has traveled this distance to my other hand. That was about six inches of traveling; to make it more challenging for myself, lets increase the distance by a foot."
Something along those lines.