TL;DR
Donald Trump maintained a deeply adversarial and critical stance toward Hillary Clinton, particularly concerning her private email server and political conduct.
Key Points
He publicly asked Russia to find missing emails belonging to her in July 2016, around the time Russian actors targeted her email accounts.
He repeatedly accused her of lying regarding her handling of classified information via her private email server.
In 2008, he publicly praised her, noting he liked her and her husband, and cited donations made to her past campaigns.
Summary
Donald Trump consistently portrayed Hillary Clinton as an untrustworthy and corrupt political opponent throughout his campaigns and presidency. Key to his sustained criticism was her use of a private email server while Secretary of State, which he frequently framed as evidence of dishonesty and a national security risk, often asserting she 'lied like a dog' about the matter. He also accused her of colluding with foreign actors, such as Russia, and encouraged the audience at rallies to chant for her investigation or incarceration.
Despite this fierce opposition during the 2016 election cycle, there existed a history of more amicable relations between the two New York residents. Prior to his presidential run, Trump had, in earlier years, called the former Secretary of State "terrific" and admitted to donating to her campaigns, stating he contributed to everybody because he was a businessman. His definitive position shifted dramatically upon entering the political arena, transforming his former acquaintance into the central figure of his opposition.
Frequently Asked Questions
Donald Trump's primary criticism centers on Hillary Clinton's handling of classified information via her private email server while serving as Secretary of State. He consistently characterized her actions as dishonest and a threat to national security.
Yes, prior to his 2016 presidential campaign, he had expressed admiration for her on several occasions. He once called her a 'terrific woman' and explained past campaign donations by stating he supports people who support him.
He frequently stated that she lied about her private email server and that the emails should have been turned over. The subject was a central theme of his 2016 campaign rhetoric.
Sources4
Donald Trump on Hillary Clinton: She lied like a dog on her emails
When Donald Trump Praised Hillary Clinton
Trump asked Russia to find Clinton's emails. On or around the same day, Russians targeted her accounts
Trump accuses Hillary Clinton of colluding with Russia as crowd chants 'Lock her up'
* This is not an exhaustive list of sources.