I am copying this from a recent blog post that I've written. Hopefully it's good advice. Let me know what you think.

3) What did I learn?
Now you might want to ask: after 500 talks, presentations, keynotes and the like, what did I learn?

Many things, among which:

3.1) Somebody in the audience is smarter than you: no matter how smart, focused, sharp you are, you’ll always find someone who is smarter, more prepared, more skilled. Which means: be humble, and if you don’t know something, just say so. People don’t pretend that you know everything; they just want you to be honest.

3.2) Slides are only a small part of a presentation: you present to inspire, and possibly to provide knowledge and details. Slides are not the main part… The most important part is telling a story, involving people, showing passion, making things memorable.

3.3) Always be listening. I mean it. Even when you’re on stage, speaking.

Don’t just listen to WORDS. Listen to feelings as well.
I’ll tell you a little story to explain this point.
Late 2009. I was in France, and I was the last speaker before lunch. I was supposed to speak at 12:30, for about 30 minutes. However, previous speakers took more time than expected, and one of the big sponsors pretended to have their CEO speak before me, unplanned, for more than 20 minutes, reading some text the entire time. READING. No slides, no interpretation.
Why didn’t he simply email all of us, instead?

His message was very boring, very corporate, full of vaporware. His last words were about how customer-obsessed his company was.

He was using people’s time as he pleased, without even thinking about their needs.
When it was my turn, it was already 13:00, and people really wanted to go to lunch.
I was angry. I was in a difficult situation.

I introduced myself, and then told the audience: “My talk was planned to be 30 minutes long. However, we are late, and you are hungry. I’ll cut my talk down to 15 minutes, and then we all go to lunch at 13:15. This is what I call customer obsession.”

Big round of applauses. The crowd was mine.
So, the lesson is: if you want to deliver a message, the length of the message doesn’t count. Other things count.
Or, if you want to be a Technology Evangelist, don’t FORCE the message to your crowd. Use empathy.

3.4) Get inspired. I have amazing colleagues that inspire me every day. Our CTO, Werner Vogels, is one of the best public speaker I’ve ever seen, perhaps second only to my all-time favorite, Matt Wood (a rare combination of intelligence, humility, knowledge and a collection of PhDs), who recently moved to a new role, Chief Data Scientist. Our most senior Evangelist, Jeff Barr, is a walking encyclopaedia on all things AWS. Jinesh Varia is a talented, super-smart producer of high quality content, and a good presenter too. And there are other colleagues (like Simon Elisha) which, despite not strictly being Technology Evangelists, are amazing speakers nevertheless.

There are also a lot of amazing Technology Evangelists out there, not just within the Amazon Web Services team.
I loved reading Kenneth Reitz’s blog post about his experience at Heroku.
So the lesson here is: get inspired, as much as possible. Never stop learning and improving.

3.5) I’ve mentioned above that “It doesn’t necessarily make sense to travel like this, though”.

In fact, after 500 talks, I think that I should focus on quality, rather than quantity. Let me be more clear.
At the beginning, you should do as many talks as possible, simply because you learn a lot, and you mostly learn by doing.
After a while (500 is enough, but also 200 would be enough), you will notice that you’re not improving so much anymore. It’s time for you to start focusing on quality. Quality, in this case, means committing your time and energy to events that matter. It could be a small user group, or a huge conference, but as long as it matters, it’s ok.
It will actually be easier for me now, since I am focused on the Bay area, and therefore travelling time is not as much as it used to be… Which means I can afford to do more events, while keeping the “quality” high.

3.6) You’re a public figure representing your company, learn how to deal with it.

This was a tough one to learn, and I admit it wasn’t easy for me, but eventually I’ve learned it the hard way. Different companies might have different policies, but in most cases you are not “just one employee”, whatever you do online or in public matters a lot.

Ah, and by the way: Opinions expressed here are my own and do not necessarily represent those of current or past employers. Just in case.

Source: http://www.brunozzi.com/2013/01/04/500-times-on-stage/