Well, at the operator level, my recommendation for good messaging is to make this small tweak to MDMP:

During MA, have the entire team drill into the question of "what message do we want this operation to communicate?" Then, coming up with a proposal, provide it to the commander during the MA brief along with the intel dump and the proposed restated mission.

Then, when the commander gives his planning guidance, he needs to give his message guidance at the same time. As the ops guys work up COAs, they shape them to communicate that message; and as they build their COA comparison matrix, they include the criteria (and it should be weighted) of "COA communicates the desired Strat Com"

Then when you brief the COAs to the commander, the message is woven in, and is not a strap-on product that you had the PSYOP guys work up in a corner somewhere.

Key to remember is that good messaging is 80% what you do, and only 20% what you say. Build your message into what you do.