1. Your handshake
Several Quora users admitted they judge people based on their handshake.
"Strong handshakes usually reflect a strong and confident character, whereas weak handshakes usually indicate a lack of confidence and are almost always a characteristic of people who would look for an easy way to do things," writes Julian Parge.
Research backs up the idea that your handshake can reveal certain aspects of your personality: One study found that people with firm handshakes were more likely to be extroverted and emotionally expressive and less likely to be shy and neurotic.
2. Whether you show up on time
Late for a very important date? The person who's waiting may be forming a negative impression of your personality.
"A proactive person will be there on time, because he is self-motivated, mentally organized, and values time whereas a procrastinator will be running here and there at the last hour," says Humaira Siddiqui.
According to science, those who are chronically late aren't necessarily inconsiderate people — but they're probably more laid-back, "Type B" individuals.
3. How you treat restaurant staff
Multiple users said they pay close attention to how other people interact with waiters.
"I will never, EVER date a man who is rude to restaurant staff," says Sati Marie Frost.
Even top execs say you can learn a lot about someone based on the way he or she treats waiters, hotel maids, and security guards. Ron Shaich, CEO of Panera Bread, says he once declined to give someone a job partly because she was nice to him but rude to someone cleaning the tables nearby.
4. Where you look when you drink out of a cup
Writes David Junto: "A person that looks into the cup when drinking tends to be more introspective, self-aware, idealistic, and focused. A person who looks over the rim of the cup when drinking tends to be more influenced by others, more environmentally aware, carefree, extroverted, and trusting."
And don't even get started on what your drink choice may signal to others.
5. Whether you bite your nails
Sushrut Munje has strong views on people with bitten nails, saying that it's a sign "the person eats away at himself."
Meanwhile, research suggests that those who bite their nails (or pull their hair, or pick their skin) tend to be perfectionists, unable to fully relax.
6. Your handwriting
Whether you're writing a to-do list or a love note, your handwriting can say a lot about you.
Ramesh Nagaraj believes that "people who put a lot of pressure on pen and paper to write something are usually stubborn in attitude. They have a lot of confidence."
Meanwhile, professional graphologist Kathi McKnight says large letters indicate that you're people-oriented, while small letters suggest you're introverted. Letters that slant to the right can mean you're friendly and sentimental; those that don't slant at all might mean you're pragmatic; and letters that slant to the left suggest you're introspective.
7. How often you check your phone
An anonymous Quora user writes about noticing "where and when [people] pull their phones out (waiting in a short line, talking to their parents, being out with friends, when they're alone in public)."
As for what it might mean if you're constantly refreshing your email or Facebook feed, one study found you may be less emotionally stable and trying to boost your mood.
8. Whether you make eye contact
Munje says a limp handshake and a lack of steady eye contact "shows lack of self-control, required drive to follow through, and a weak will."
Alternatively, psychologist Adrian Furnham, Ph.D., writes in Psychology Today that extroverts tend to look more often and for longer at their conversation partners than introverts do. And in general, people who look at their partners more often are more confident and socially dominant.
9. Your selfie style
Research suggests that people will assume a lot about you based on your selfies.
Usually, those assumptions are inaccurate — for example, being alone in a photo does not mean you're neurotic — but people are probably right to think that positive emotion in a selfie predicts openness to experience.
10. Your taste in music
Citing a 2003 study on the topic, Quora user Humaira Siddiqui says she judges people based on the type of music they listen to.
The study found that people who listen to "reflective and complex" music tend to be open to new experiences and politically liberal. Those who listen to "upbeat and conventional" jams are more likely to be extroverted and athletic.
11. Your favorite color
Shivani Jha has a theory on what your color of choice reveals about your personality. For example, if your favorite color is red, she assumes you desire physical fulfillment; if your favorite color is yellow, she thinks you need logical order and value individuality.
Industrial psychologist Bernardo Tirado, PMP, breaks it down slightly differently. Writing in Psychology Today, Tirado says red-lovers are tenacious and determined, while yellow-lovers enjoy learning and find happiness easily.
12. Whether you're a dog or a cat person
People may make inferences about you based on your pet. For instance, Joe Waldron believes people who do not like cats have control issues, and he warns against dating women who have big dogs, believing they are not interested in long-term relationships.
Meanwhile, one study found that people who prefer dogs are generally more energetic and outgoing, while those who prefer cats tend to be more introverted and sensitive. The same study also found that cat people tend to be more intelligent.
13. How long it takes you to ask a question
Even if someone doesn't say anything about themselves in conversation, you can still learn about their personality.
As Khaliana Schmitz says: "When meeting someone for the first time … see how long it takes for them to ask you a question in return. You'd be surprised how much this reveals in terms of a person being a 'giver' or a 'taker.' It will help you distinguish between 'people who like you' and 'people who like what you can provide them.'"
