To use the vernacular: I am with Her. While I make an effort to avoid wearing blinders in my analyses, including this one, I have my biases, including that I support Hillary for President. Indeed, this is more about how she should approach that first debate rather than a perspective on how it may proceed.
In that vein, I don't like that the polls are tightening but it doesn't surprise me at all. As the election approaches, particularly with Trump's recent attempts to soften his persona, more and more folks who lean Republican are likely to return to the fold.
I agree with many that the first debate may well be decisive, or at least extremely important. As some have remarked, it is Trump's best opportunity to get back into the thick of things and he has a charisma that Hillary lacks. He will be loaded for bear, primed to fire off all kinds of allegations against her, mocking her FBI interview and her use of the private email account and server, focusing on a world in turmoil and her role in bringing it about, mentioning her remarks about Benghazi and the death of the Ambassador, identifying her most notable flip flop on TPP as well as on incarcerations and criminal justice reform, and, of course, underscoring the lack of trust that Americans feel toward her. And, let us not leave out pointing a finger at her for allegedly being an enabler for Bill's sexual escapades. Then, too, there are the Goldman, Sacks speeches and payments, her Wall Street connections, and claimed improprieties relating to the Clinton Foundation.
Hillary's challenge will be to focus from the first minute on his unfitness for office. His birther campaign against Obama which he now tries to bury, his encouragement of nuclear proliferation including in the Korean peninsula, his waffling on NATO in evaluating whether NATO allies deserve defense at the time of attack based on their prior financial contributions, his opposition to any legal status for undocumented immigrants despite confused efforts to waffle on that position, his incendiary comments about Mexicans and mass deportation no matter how he has tried to walk them back, his self-inflated notion that Mexico will pay for his incredibly gorgeous wall, his hypocrisy when it comes to trade and increasing manufacturing jobs in this country given his decisions to manufacture products abroad, his comments that wages are too high and opposition to an increase in the minimum wage despite his efforts to be the “voice” for working class folks, his support for abolishing the estate (death) tax that favors his family, his ridiculous tax plan that rewards the super-rich and creates an unmanageable deficit, his steadfast refusal to divulge his tax returns so Americans can get a sense of his own financial interests, lawsuits against him claiming fraud vis-a-vis Trump University, allegations that Trump Foundation engaged in bribery of public officials, bankruptcies of Trump enterprises. As for his misogyny, I imagine Hillary may be somewhat constrained because of Bill although Trump's statements about women are many and demeaning. But she will attack his character at every turn, including as evidenced by Trump’s mockery of a disabled reporter, which remains, for me, his greatest single sin and most prominent direct evidence of his unfitness for office, albeit not the only evidence.
As to that first debate, in my view, Hillary needs to pounce from the very outset, put up a strong and aggressive defense against Trump’s assaults, and keep pouring it on. Every time he attacks, she needs to counter-punch, to borrow Trump's claimed strategy. But it will be a challenging encounter for her and, as many have often said about these kinds of debates, if he is seen as her "equal", which is highly likely given his entertainment background and status as a billionaire, or even her equal in pouring abuse on his opponent, he may be seen as the winner, at least by pundits who have an interest in keeping the presidential race close.
That said, if she is able to emerge the victor in that first debate, she will, in my view, and assuming nothing untoward happens before that debate, be in a very good position. Of course other things can happen after the first debate - performances in subsequent debates, an October surprise from Wikileaks' Assange, world events, and the like. But she will be in good stead. On the other hand, if he prevails in that debate or ties her, all bets are off. And I've always said, and written, that Trump certainly could win the general election. Need I remind folks, winning a third term in the White House for a political party is extremely difficult to achieve.