Donald Trump can definitely demonstrate that he is more prepared to be president than Hillary. However, Trump must start running a more serious campaign: no more name calling, insults and such bombastic comments. Furthermore, Trump needs to study up a bit more on global affairs, as well as develop a sound economic plan. In short, if Trump takes the right steps, he can demonstrate that he is best prepared for the White House.
Trump admits that he gets most of his political knowledge by watching cable TV, while Clinton has decades of experience in public service. Trump's experience is all in business, which does not translate well to running a country. He is particularly unfamiliar with foreign policy, which is Clinton's area of expertise.
Despite the fact that Trump leads Hillary Clinton currently, there is absolutely nothing to suggest that these figures won't change. The presidential campaign season changes so rapidly with opinions being swayed almost daily, so Hillary Clinton may well surge back into the lead in the near future. Although Trump can try to demonstrate he is prepared for being elected as President, Hillary Clinton is just as capable of doing so and will no doubt be working her hardest in order to do so.