1. People lie. Don't expect your opponent to tell the truth. Be prepared to surgically extract the truth.
2. A good attitude goes a long way. As a lawyer, party or witness, your attitude can really impact the case. Judges and juries have to make a lot of “close calls.” If you are positive, professional and respectful, you are more likely to be liked and believed.
3. Appearances matter. Appearances affect how we feel about ourselves and how others portray us. A little confidence is a good thing. However, when it comes to the appearances of attorneys, clients and witnesses, the safest approach is to look good, but not too good. Generally speaking, you (and clients) should err on the side of dressing conservatively. Cufflinks might not be well-received by a rural jury. Exposed tattoos are risky. ALWAYS consider your venue and audience.
4. For the most part, you can't change the facts or the law. Sometimes you can't play the role of hero and must resort to damage control. That doesn't mean you're losing, it just means you have to adjust your expectations and redefine a "victory."