Surprisingly, my answer isn't all that different from "Strategies for dealing with ADD" and they're not different from "How to prototype effectively".
It all boils down to protocols, practice, focus, and subject matter.
First, for my own personal development, since 2012 I've been making it a practice to meet with someone "inaccessible" at least once a month. I find someone who I don't have any business speaking with but (and this part is important) who I genuinely needed advice from. I don't just reach out to people because I want to say "I reached out to so and so". The point was, at a frequency of once a month, I am guaranteed to have a problem I need help solving. And if I am going to get advice, I should try to get it from the best. And then prove to them I was worthy of their advice so I can honor the time they invested in me.
Also, inaccessible doesn't always mean famous (often just famous to me). I remember randomly reaching out to Jan Paul Posma, for instance, because my life goal is to (in may respects) become more like him. He's worked with wikimedia, is a fantastic visualization designer, is extremely knowledgeable about web annotations, and is all around just a philanthropic person more people should try to emulate. Why not me? Why not ask if I can treat him for coffee and learn how and by what circumstances he got to where he is. I've similarly reached out to the head of Chicago University's institute of knowledge, and several data mining, AI, and NLP experts from whom I wanted to learn about their research.
Do your research. Sorry for my language, but one thing I learned from Oliver Yeh is: Do Your Damn Research. I think Oliver and I are both playfully competitive with each other re: rock climbing, so I can't admit it to his face, but Oliver is a great guy, a heck of a businessman, and he gave me some of the most sobering and best feedback I've ever heard. Real radical candor worth paying for.
I was sitting with him at his SensorTower office a few years back (he was nice enough to meet with me to offer advice) and I asked him if he knew any investors who I should be speaking with. In more or less words, he basically said, "Come on, you need to do your research. There's no reason why you can't go through my linked in and see for yourself who's a good fit. Why should I have to do this work". And I couldn't help but thing. Frick. He's completely right, this mistake should never happen again. He was nice about it, but his radical candor was something that was a critical development for me and for which I am very grateful.
Since then, and also because of feedback and an amazing precedent from Joe Polastre, I've been keeping a list of people I need to speak with, as well as a list of the people who are connected to these people. I do research both before meetings, and before asking for introductions to make its clear why the introduction is necessary and why it needs to be the intro'er.
Apart of the research process is seeing how they write (if you've conversed with them before or read their essays) and trying to value their time. Demonstrate what about their work convinced you that your question must be answered by them. Show them what the products of your work will be once you have an answer.
Return the favor. I work really hard to connect my friends to people in my network. Because of Oliver's feedback, and to hopefully help others avoid similar embarrassment down the road, at the end of my meetings I offer people the chance to look through my linkedin and offer to connect them to people if (a) I know the recipient well enough to respect their privacy and time and (b) because there's a necessary reason.
Having genuine intentions. I think one of the biggest reasons people respond to me is because many of the projects I work on are philanthropic. I work on mostly open source projects, in a selfless capacity (often trying to protect people's freedoms), I work at a non profit, and I try not to capitalize on other people. Perhaps it's Machiavellian, or maybe it's just a positive externality; it's simply a fact that having philanthropic threads in your life can make it easier to establish foundations for strong relationships and can empower you to explore followup opportunities in the future.
Another policy which is important to me is, "anyone who is worth meeting, is worth treating". Being a generous person and earning this reputation only makes it easier to meet with others in the future. The more meetings you setup, the more you feel in your own skin when you reach out to people, and the more natural the exchange is. Also, don't be afraid to be persistent.
Be in the right communities and networks. Your job and affiliations partially determine who you have access to. If you are at an early stage startup, be aggressive and ask to be included in advisor meetings. This led to me meeting all sorts of interesting people like the former CEO of CNN, an early VPE for Facebook, strange serendipitous conversations with Ashton Kutcher and MC Hammer.
Ask questions which are extremely easy for the person you're reaching out to, to answer. In addition to "do your research". Also, "do work upfront". Figure out where peoples' offices are. Suggest locations to meet around them. Offer times they can pick. Let them answer with yes.Peer review. Ask your friends if you can read some of their emails which worked well for them. Have them read over your drafts. Try the same email you're planning to send, but to someone else r
epresentative of the person you're actually trying to reach (see how it performs).
Become exposed to that which you don't know. Look, sometimes this stuff is really obvious but unintuitive, like we just don't think about it. I remember when I was working at Hyperink (we had a perk of Friday reading time), I picked up this weird book How to Win Friends and Influence People which I could not believe existed. I was almost offended that it was on our bookshelf. And well, actually it was pretty incredible. It offered stories rather than a template and allowed me to come to my own conclusion. More than anything, it gave me a window into how people might think, beyond their actions. Understanding people and listening to people is critical to this whole formula.
In short, do your homework, have a darn good reason, become the person that is worthy of a response, prepare the field for victory (in the Sun Tzu sense), be a genuine person, and leverage the resources in your network to increase your chances. And when when there's no response, don't give up. Meet those who work for the person and ask them for an introduction. Find out who this person works *for*. Reach out to them. Figure out who the person's friends are. Get in touch with them. And if you get a no, understand why, improve yourself or your cause, and then if it's really necessary, reach back later with your updates.
If I hadn't done this, I would have never flown to San Francisco with Stephen Balaban after being rejected the first time around by YCombinator and then (nearly) demanding (after 3 additional emails) that we deserved another shot. After our talk w/ PG (rejected again and accused of saying "innovative" a lot), I wouldn't have had the idea or the confidence to reach our to Kevin Gao and Matt Lee to discuss collaboration. I would have never connected with such amazing advisors and mentors. I wouldn't have had a chance to learn from Oliver. I wouldn't have been able to reach out to open access institutions and grow Open Journal Foundation to over 20 organizations. Or had the audacity to believe I could also rally troups to protect net neutrality. I wouldn't have met Jan Paul Posma. I wouldn't have had the guts to reach out to Entelo and become one of their early tech advisors. I would have never gotten VC meetings with the likes of David Hornik, Michael Neril, and Simon Rothman. I wouldn't have connected with over 250 artificial intelligence phds who became the @Hackerlist, Inc network. In short, I wouldn't be who I am today if it wasn't for the support of a lot of people who were willing to click reply and invest a little bit of faith in me.
In the words of the late great Randy Pausch, "Brick walls are there to give us a chance to show badly we want something"