Normally you greet each other, smile, say something like 'hello, it's a pleasure to meet you', and it's normal to shake their hand. Then they'll usually invite you to sit down. I'd follow their lead. Obviously if they're still standing wait to be asked to sit down. Then it's usually for maybe a little small talk before they go into the questions.

Is this a job interview? First of all, it is never wrong to say "hello" when you first meet someone. Also, remember to say "thank you" and "nice to meet you" at the end.

The obvious one first impressions count! You have no idea how true this is. Ask any psychologist. You need to smile and make sure you have a firm handshake without breaking anyone’s bones. Eye contact is vital so keep your gaze just a few seconds longer than usual, without looking like a lunatic.