Knowing how to small talk is an art. It sounds silly, but talking about the weather is a good thing to do when you are in a job interview. There are lots of opportunities for you to prove that you are fun, easy to talk to, and have a good attitude, not only when you are sitting face-to-face with the hiring manager in a conference room. Everyone you meet will have an opinion, and everyone you meet may or may not provide input. Remember that.
So, when you are being walked from meeting to meeting, or waiting in the lobby, or have an idle moment when someone asks you if you want coffee or water, be ready to make some small talk.
What is small talk, exactly? Small talk is neutral. Topics should be safe. Meaning, if you bring up a topic, you need to be sure that no one has a strong negative opinion about it. And you also need to be sure that the conversation does not reveal anything that someone could interpret as a negative about you.
So. If someone asks you if you found the place okay, or how was traffic, or did you get lost? Tell them it was easy to find and no problem at all. Even if it was a nightmare. You don't want to come across as a complainer.
Stay way from politics, sports (what if you love a team that your hiring manager hates?), religion or jokes.
What's safe? The weather, where you ate last night, or a heart warming story everyone heard about on the news.
There are ample opportunities to come across as cool, easy to talk to, easy going. If you see someone juggling an arm full of things and trying to open a door, go help. If someone asks you if you need anything, say, 'no' or be very low maintenance. Everyone you interact with, from the person at the front desk, to people walking through the lobby, to the HR manager, will all have an opinion. And you have it in your control to make a great impression.
There is no worse feeling than realizing you said something stupid, and worrying if you blew your chances. If you take a minute to prepare, and think before you speak, you will be fine.