One of the most important philosophers to read for your personal development is Aristotle. Also, read the book of Proverbs. It has hints for becoming charismatic, managing your money, flirting, being happy, and even going to heaven.
In his rhetorical manual, Aristotle observes this (just read the bold to get the main point):
But since rhetoric exists to affect the giving of decisions—the hearers decide between one political speaker and another, and a legal verdict is a decision—the orator must not only try to make the argument of his speech demonstrative and worthy of belief; he must also make his own character look right and put his hearers, who are to decide, into the right frame of mind. Particularly in political oratory, but  also in lawsuits, it adds much to an orator’s influence that his own character should look right and that he should be thought to entertain the right feelings towards his hearers; and also that his hearers themselves should be in just the right frame of mind. That the orator’s own character should look right is particularly important in political  speaking: that the audience should be in the right frame of mind, in lawsuits. When people are feeling friendly and placable, they think one sort of thing; when they are feeling angry or hostile, they think either something totally [1378a] different or the same thing with a different intensity: when they feel friendly to the man who comes before them for judgement, they regard him as having done little wrong, if any; when they feel hostile, they take the opposite view. Again, if they are eager for, and have good hopes of, a thing that will be pleasant if it happens, they think that it certainly will happen and be good for them: whereas if  they are indifferent or annoyed, they do not think so.
W. Rhys Roberts, “RHETORICA,” in The Works of Aristotle, ed. W. D. Ross, trans. W. Rhys Roberts, E. S. Forster, and Ingram Bywater, vol. 11 (Oxford: The Clarendon Press, 1924).
The point Aristotle is making is about speech giving, but I think it is also a useful point for things like making friends and avoiding unnecessary conflict. Aristotle is noting the importance of maintaining and producing a certain frame of mind when you have social goals (in this case debating or convincing a crown during a speech).
But is it possible to apply these principles outside of the categories to which they are traditionally applied? I think so.
For instance, if in a conversation you make a joke and people treat it immediately like its offensive and that you are a bad person. You have a few options based on the idea of people’s frame of mind:
- Immediately and profusely apologize (thus admitting that you really meant what you said to offend), thus making the social event about you and your bad character.
- Act hostile and thus make the situation about you and your bad character.
- Find some way to take the joke further or in a different way so that people realize that the point is to be funny, not cause hurt feelings. One could, if it is perceived that genuine harm was caused, apologize as well.
As a younger man, I had no idea how to do these things. And it is difficult, because keeping a group’s frame of mind friendly when one is insulted is the least of your worries when your social fight or flight response is going a mile a minute in your head. But, like the man said, “[w]hen people are being friendly and placable, they think one thing…”
A skill that is very important for pastors, debaters, evangelists, spouses, or nerds looking to make friends is to maintain a calm state of mind under social pressure. When this is accomplished, one can more easily be friendly (do unto others) while still refusing to capitulate to a false idea, a bad argument, or responding unduly to a playful insult. This does not mean anything like, “never admit fault.” Admitting fault when wrong is perhaps the first step to virtue (1 John 1:9). The example of the joke was just an example, not a principle. Rather, I mean to illustrate that maintaining a positive and amicable thought pattern in the midst of disagreement (which most people take for hostility these days) or hostility is very important for being an intellectual as well as a social and pleasant human being.