Use breath mints.
Interviews are stressful, and stress leads to bad breath.
Pop a breath mint at the start and one after lunch.
Or just eat one at the beginning of every round.
Drink water.
Being on your feet and speaking the whole day is exhausting.
You become dehydrated and can even lose your voice, especially after multiple interviews in the same week.
You will be thirsty on the drive home too.
After the first couple of onsites, I bought a case of bottled water and kept it in my car. It made everything smoother.
Dry your hands thoroughly.
This might sound trivial but it's not.
I've been peeing at tech companies for over a decade and more than 50% of us don't even pretend to dry our hands.
It doesn't matter on the average day,
but during an interview you might have to shake someone's hand immediately.
What if the hiring manager or CEO stopped by to say hi?
Trust me, you don't want to be remembered by your soggy handshake.
Wiping a couple of times on your jeans won't cut it. Dry your hands thoroughly: front, back, and between your fingers.