Suppose, as now appears likely, it’s going to be Trump against Clinton. Let’s think this through from Trump’s side.
Trump’s big disadvantage is that he scares people. He is crude, aggressive and over the top. His advantage is that many people find him authentic and authoritative. It would be a mistake for him to respond to his vulnerability by becoming more scripted and “nicer”, since that would undermine the aspect of his appeal that has played the largest role in getting him to this point. Rather, he should try to maintain the personal aura he has established while diminishing the fear factor.
Given this, here is what I’d recommend: go after Clinton as a hawk. She is a hawk. Her history of support for military interventions and attachment to neocon advisors is there for all to see. Trump has the opportunity to present himself as the less threatening, more reasonable candidate on the one aspect of presidential power where fear—fear of war and foreign threats—drives public opinion.
At the same time, Trump should, from a political strategy perspective, continue to be Trump. (He may not be able to change this.) He should say outrageous things off the top of his head, act macho, and cement his image as an anti-politician. Combining this with striking a moderate pose on military adventurism would maximize the advantages of his style while minimizing the disadvantages. He should be grateful that his prospective opponent in the general election gives him this opportunity.
Campaign ad, sometime this summer, Trump in front of a large, cheering crowd: “Let me tell you straight: I’m honest and I’m tough. I like to set clear goals and make sure they’re met. But I’m not dangerous. The other candidate, the one who smiles a lot and whose every word is written by someone else—she’s dangerous. She’s always looking for new places to bomb, new wars to get into. That’s not me. Tough, yes. Dangerous? Not for the American people.”