She would NOT spend two hours or more tweeting and watching TV every morning. She would not retweet offensive and mendacious videos made by extremists.
She would hire competent advisers and then LISTEN to them. She would not undermine them, and would not seek to set them against each other.
She would understand that the executive, legislative and judicial branches are separate but equal. She would not imagine she was a dictator.
She would not offend our allies, or taunt our adversaries.
She would READ, and make a serious attempt to understand the issues with which she had to deal.
She would not LIE CONSTANTLY. She would not brag vulgarly and embarrassingly about her own nonexistent, irrelevant, and embarrassing achievements.
In short, she would behave like an educated, experienced, qualified adult. Not an infant that needed its diaper changed.
There's much more, but working up a complete list would take all night.