My advise to Trump. Which he in all likelihood won't take but which I present with honesty.
After WW2, America ruled half the world, the so-called free world. It led or ran just about everything. But,
1) The era of America solving any problems in Asia is over. Get out for your own good.  
2) The era of America solving any problems in Europe, Middle East is over. Get out for your own good.
3) The world other 3 biggest and most powerful countries - China, India, Russia, do not need any of your help or interference. They have their own systems and thinking. Leave them be. Get out. 
3) The era of America solving any problems in your own country is almost over. Don't make enemies out of your neighbors - you have far too many enemies already. Jettison all failed ideologies in America and solve practical problems with rationality. How? Borrow what FDR did. Add a huge dose of sound science. This is your last chance. 

You have another 100 days. That's it.