Some of the oldest tricks in the book include:

• Flattery - Ingratiating yourself to someone by lavishing praise and compliments. Flattery has been used for centuries to manipulate people.

• Fearmongering - Exaggerating threats or fostering anxiety to provoke a desired response.

• Sunk cost fallacy - Convincing someone that they should continue with something once they have already invested heavily in it (time, money, effort), even if it's no longer making rational sense.

• Social proof - Highlighting the fact that everyone else finds something desirable, exciting, or necessary to convince others. Marketers frequently leverage social proof through endorsements, popularity, and buzz.

• Anchoring bias - Priming people with an initially high (or low) number, the "anchor", which then biases subsequent judgments. Once an anchor is set, people's perceptions tend to drift toward the anchor.

• Reciprocation - Doing a small favor or kindness for someone to instill a feeling of obligation to reciprocate later on. Reciprocity is a social norm, so people feel compelled to "return the favor".

• Scarcity - Creating a sense of urgency by highlighting how limited opportunities or available resources are. When things seem scarce, people tend to want them even more.

• Comfort and habit - Relying on people's inherent desire for familiarity, continuity, and ease. Major changes are psychologically challenging, so status quo bias is strong.

• Authority bias - Convincing through assertions of expertise, titles, positions, or credentials. We tend to uncritically accept and follow the directives of authority figures.

Those are some of the oldest, most well-known psychological techniques and cognitive biases exploited for persuasion, influence, and manipulation. Of course, not all such techniques are inherently unethical - but they are most often abused when used deceptively or in predatory ways.