He is not going to be throwing nukes around the place, despite what people think he ain't that stupid, hopefully he will listen to the analysists etc, but he wont be in any rush to help countries when Russia (as someone said the Baltics) and China (in the South China Sea) start flexing their muscles, he will quickly find out there is no-easy quick fix in the Middle East.
As a businessman he does think he knows better then the economists about the economy, and he can do long term damage there, he will get rid of the vast majority of banking regulations, and of course London will have to follow and we all know how that turned out, he wont care about balancing the budget, will reduce personnel taxes and corporation tax, grand for short-term popularity but will cause long-term problems.
He will put in extreme right wing supreme court judges, so abortion bill, gay marriage etc will be in the firing line etc.
He wont be able to do his extreme headline acts, immigration, the wall etc.