If used correctly, these principles make you unstoppable. If used unethically, they make you a fraud.
1. Urgency
Time constraints make people act (think: limited-time discounts).
2. Scarcity
Quantity constraints drive action, too (think: only 5 items left in stock).
3. Status
People like being seen as better than others (think: sports cars, watches etc.).
4. Loss aversion
The pain of a loss exceeds the pleasure of an equivalent gain (think: don’t miss out on this 50% off sale).
5. Social proof
People like to copy others, especially if those others are credible in their eyes (think: celebrity endorsements).
6. Reciprocity
We feel uneasy when we don’t return favours (think: free samples).
7. Consistency
We’re inclined to follow through on things we’ve said and done in the past (think: this is why politicians accuse each other of lying).
8. Liking
We’re more easily convinced by people we like (think: building rapport on a sales call).
9. Anchoring
We judge prices based on other prices we’ve just seen/heard (think: lowball buy offers).
10. Emotion, Then Logic
We buy with emotion and justify with logic (think: the salesman lets you sit in the Ferrari, then tells you about the fuel economy).
Once you start spotting these (and similar) phenomena in daily life, they're hard to unsee.
In my experience, it's worth spending a disproportionate amount of time learning to do this. Every time I underestimate the importance of it, I get a painful reality check.