The best one I ever heard was, apparently, if you have a warm hand when you shake somebody’s hand, you immediately become a more desirable person to get along with.
- Stand up straight, no slouching, hands out of pockets, and head held up high. It’s not just a cliche — you literally feel better and people around you feel more confident in you.
- Not always a must, but try to dress well for important occasions (including interviews). If you look good, you feel good; and if you feel good, you’ll do good.
- In a negotiation setting, always start by anchoring, meaning start on a more radical extreme end of what you expect to get. That way, you and the other side can work to that result, rather than you locking yourself out of it.
- Avoid saying “I think,” and “I believe” unless absolutely necessary. These are phrases that do not evoke confidence, and will literally do you no good.
- When playing a game of cards with casual players, mutter to yourself the exact opposite of what you want to happen. So if you want your opponent to fold, then mutter, “Please don’t fold, please don’t fold…” An overwhelming amount of times, the opponent will fall for the bait.
- When feeling anxious, clean up your house/apartment. You will feel happier and more accomplished than before.
From an academic standpoint, this is mostly just armchair psychology; but from a real-world standpoint, these have all worked very well in my personal and professional lives.