Body language at interviews
So you're not drunk and you've made the effort to polish your shoes. Good effort. Your manner and your dress sense certainly say a lot about you, but your body could still let you down.
An equal handshake
Try to mirror their grip it avoids any dominant/submissive vibes.
Relax into your chair
The way you sit conveys a lot of subtle information to the people on the other side of the desk. If you look relaxed, it'll encourage your interviewers to feel at ease in your company. Just be careful not to take it to extremes, and kick back like you're at home on the sofa. Flipping the chair round and straddling it is also just a little too cocksure.