Appearances can be deceptive. Don't be fooled by friendly faces. If you sense a trap, you are probably right.
Pad and pen
Have a pad and pen handy. You'll be given clues that could come in useful later on.
Stamina
If you lose over half your stamina in a fight, don't bravely soldier on. It could leave you in a near-unwinnable scrap later on. Keep trying until you come out with the bare minimum of damage.