May 2008 (perspective of a Ph.D. student)
Here are some observations regarding knowledge and expertise that I've learned from my parents, friends, colleagues, mentors, and my own experiences.
A friend is the best starting point for learning about a new topic
Whether it's what new digital camera to buy or how to do your taxes, the best starting point for information lies in people you know. In the Internet age, there is a temptation to simply Google a bunch of key terms to try to gain some expertise. While certainly better than doing nothing, an undirected search can lead you down unpromising paths, waste your time, and at worse, provide you with misleading information (not necessarily because the websites are untrustworthy, but merely because their contents might not be your optimal information source).
Instead, a better starting point is to think about which of your friends or acquaintances are knowledgeable in digital cameras, tax laws, or whatever you want to learn and then politely ask him for advice. Depending on how well you know this person, how much he knows about this subject, and how deeply you care, you could solicit advice through email, phone, or an in-person chat over coffee. At worse, even if your friend doesn't have the time or know-how to give you a satisfactory answer, he can at least point you in the right direction by telling you what books or websites are worthwhile to read, thus allowing you to begin your search at a more advantageous starting point. Email is a powerful medium for soliciting such quick advice because your friend can simply send you links to promising websites or books on Amazon whenever he has free time.
In the best case, you and your friend engage in a productive hour-long chat where she teaches enough for you to be satisfied. This isn't hard to achieve if you are genuinely interested in the subject matter and your teacher has some leisure time, because people love talking about topics in which they are experts. This is one of the aspects of human nature that my father has taught me to recognize ever since I was young. He showed me that even the shyest, quietest, most introverted person will open up and be exuberant when she is talking about something that she knows better than others.
My father repeatedly told me that truly smart people capitalize on the smartness of others and reciprocate with genuine appreciation and gratitude, which makes it a win-win situation for both teacher and learner. Not only are you learning something valuable, but you are also strengthening your relationship with a friend. Doubly nice!
Get several independent expert opinions by sending each person individualized but identical emails
For concrete questions like the trade-offs between purchasing a PC or a Mac or what kind of car to rent, a good way to solicit advice is to email a bunch of your friends with the same question. Email is great for such questions because it allows you to craft your message precisely and your friends to respond at their leisure (rather than, say, putting them on the spot with an intrusive phone call). Keep the email terse but polite in order to maximize the chances of a response.
An effective trick to get more responses is to email everyone individually (with identical or near-identical emails) rather than as a group. If you email an entire group, then each individual might suffer from the bystander effect, not bothering to respond because he thinks that someone else probably already plans to respond earlier. On the other hand, the advantage of a group email is that people can discuss and debate back-and-forth on the thread. In that case, make sure to encourage people to 'Reply-to-All' instead of just replying to you.
When you are learning from an expert, humbly assume the role of a student
If someone is teaching you, don't try to be a smart-ass. You'd be surprised at how often people who are trying to learn want to show off their knowledge by interrupting their teacher; perhaps it's an innate desire of not wanting to appear ignorant. But who are they trying to impress? If your friend made time to discuss digital cameras or computers with you over coffee, then she understands that you're not an expert in that area and won't think that you're a moron if you don't know much about it.
Of course, I'm not saying that you should remain silent and just nod and smile. If you ask questions, clarify your assumptions, and interact with your teacher, then both parties will benefit. But try to avoid the urge to sound smart. The smartest people I know aren't afraid to say things like "wait, I don't understand this" or "please clarify for me" because they are confident nobody will think they are dumb for asking for clarifications.
Being super smart is no excuse for being a super asshole
My friends and I have found ourselves in the presence of people who are super smart but also super assholes. Perhaps these symptoms are due to personality traits correlated with extreme intelligence, but we agreed that being super smart doesn't give anyone an automatic free pass to douchiness. Being someone that other people refer to as "that guy is an ass, but we need him because he's really smart" might be fine when you are so valuable at your local organization that nobody can replace you, but when you are in more capable company, you will be replaced by equally smart people who aren't assholes.
Somewhat counter-intuitively, one of the greatest benefits of being around lots of super smart people is that less of them tend to be arrogant. That's because everyone knows that everyone else is super smart as well and nobody has anything to prove. If a person acts like an ass, then she is strictly less respected than everyone else. Problems often arise when there is a handful of smart people in a group of more mediocre people ('big fishes in a little pond'); then the select group can have the leverage to act arrogant and everyone else has no choice but to grudgingly accept it.
Everyone can teach you something interesting
In recent years, I've mostly interacted with people like myself: highly-educated men and women in science, engineering, and business fields with degrees from top-ranked universities. I'm not so good at interacting with people from different backgrounds. When I was a child, though, I witnessed my parents interacting with people from a variety of socioeconomic classes. Something that my father always emphasized was that I shouldn't look down on people just because they didn't take the same academic path as my family did, even if we were 'better off' by some metrics of educational achievement, financial status, or social class. He told me not to ever consider myself superior to other people; instead, simply consider myself different, with a different background and set of skills.
As I grew older, I began to realize that unless you are one of those rare people who is ridiculously wealthy and/or is changing the world, you aren't much different than most people in your society—you are working to make a living to support yourself and your family and finding pleasure in recreation during your free time. Regardless of whether you are a mechanic, prison guard, chef, teacher, or research scientist, you are still using your own specialized skills to work for a paycheck.
Coming from top-ranked universities and always interacting with super smart people, I've witnessed a fair share of arrogance regarding our positions as the so-called academic elite. In reality, the academic path is only one of many options that young people take in life, and while white-collar society regards it with more respect than, say, opening a local auto body shop, my parents taught me to regard it as different, not necessarily better. Certain life paths are better for certain people depending on their strengths, abilities, and circumstances. The plumber who fixes your toilets doesn't give a crap about your Ivy League degree.
Furthermore, not all knowledge is of the academic kind; people who work in different areas have tons of knowledge that I don't, and they are way better than I am at what they do. They can teach me a lot that I don't know, and vice versa. My father was always adept at making conversations with many different types of people by asking them about subjects in which they were experts. Both parties benefit from the shared rapport—my father can learn something new, and his conversation partners can get to enthusiastically discuss something in their respective domain of expertise.