At my logistics company, we are currently hiring for an open position. (It seems like we are ALWAYS hiring for an open position, which is a good thing, I guess.) Because I sit in the HR seat there, I do all the first-touch phone screening, and then hand the people I like/think would be successful over to the hiring manager for more in-depth interviews.
I've also done all the training on interviewing for the hiring managers there, and it's pretty simple. My basic rules are: Don't ask anything stupid or illegal, listen WAY MORE than you talk, and always listen to your gut. But the most important rule I have for hiring is this—If someone isn't a HELL YEAH, then they are a no.
I want everyone we hire (at any company I own, run, or participate in) to be an absolute slam dunk. I don't want any wishy-washy hires, or "I think they'll be okay?" hires. Those never work out. In three months or six months (or sometimes in two weeks), you end up regretting bringing that person on, and the time you spent searching (and hiring and training and working with them) was a total waste, and you are either stuck with a bad fit employee, or you do the right thing and let them move on to a new opportunity and then you have to start all over again.
It's an easy calculation—knowing all that I know about this person, after rounds of interviews, when I think about hiring them, am I excited about what they'll bring to the team and the company? When someone asks me "do you want me to write an offer letter?" is the answer HELL YEAH?
Because if it isn't, it's a no.