'"Hand on the flap lever' - I have had an 'over-eager' FO select Flaps up in a B737 when I asked for "gear up". This was an 'action slip' - right action, wrong moment. Placing your hand on a switch in anticipation of your colleague calling for it is asking for trouble, and leaves you exposed to errors of this type.
Do not put your hand on a switch or lever until a) asked for and b) you have confirmed it is the correct one.
"Have you tried discussing it?" - That advice is more properly directed to those pilots who feel that putting their hands on a safety-critical lever is an appropriate form of communication! What's wrong with "Shouldn't we select flaps up now?"?!