As a person who has interviewed prospective employees for technical positions (before I became disabled) I view political campaigns as extended job interviews and elections as giving my recommendation as to who to hire. So the first thing I think about is whether the candidate is technically qualified.
In every Presidential election before this year's that has eliminated about half of the field for the primaries and almost all of the third quarter party yahoos. In some years, a third party candidate will meet that standard (Perot '92) in some not (Nader, Buchanan, Perot '96, Anderson). Never in my lifetime has the general election candidate of one of the major parties failed to meet that standard.
Donald John Trump is singularly and completely unqualified to run what is, in effect, the world's largest company. Our "company" has in excess of three million employees, more than 2/3 of whom are issued weaponry of deadly force. It has 535 members of the board of directors. And I cannot support a CEO who has never been a member of that board or the CEO of one of the states.
As far as Secretary Clinton is concerned, her errors in judgement, while extremely disappointing, do not in my mind, rise to the level of disqualifying.
However, if one insists of voting a write-in protest, I would recommend that instead of writing in Mickey Mouse or Jesus Christ or another fictional entity, that you would write in someone who is qualified to serve, either George H W Bush or Joe Biden.