1. What were your best mistakes? By that I mean the mistakes that gave you the most insight into the workings of the industry.
I made one early sale, which made me believe that whichever garbage name I'd register, I could sell it for mid $xxx or higher. I quickly learned, through registering lots of silly domains, that the industry doesn't work that way.
2. If you could start all over again, what would you do differently?
Develop and develop some more. I'd build a constant stream of revenue from a few sites, and use the money earned to buy better domains or money-making domains. I'd also register fewer made-up words in hopes that some startup somewhere would pay $xxxx for something I registered.
3. How do you believe the industry will change in the future? What direction do you think it's heading in?
More and more companies are realizing the potential of call-to-action domains. When the average person watches a TV commercial -- a US Navy commercial, for example -- a URL is normally displayed on the screen. For years, it was normally just the organization name + dot com; for example, usnavy.com. Recently, however, marketers have realized that they're more likely to bring in views with a "different" URL listed on their commercials. The US Navy responded with listing a new URL in their commercials and print material - DoSomethingAmazing.com. It inspires the reader and makes them more willing to visit the site. If you look around carefully, this is happening everywhere.
I also believe "short domains" are on their way out. Don't listen to buyout hypes. The recent three-letter .com price bubble is a good indicator of how domainers artificially inflate the price of a certain type of domain. Don't buy LLLL .nets or LLLL .info. It's beyond me why anyone thinks these are good investments. LLLL .com is barely keeping its head above $20 apiece for the lowest quality names, and LLLL .net usually fetches 1/10th of the price of a .com or less. LLLL .info is 1/10th of .net, and nobody uses a four-letter made-up word on a .info. Be realistic and rational.
Domain parking is on its way out, as is PPC revenue. Development will be key in coming years. Keep in mind that video advertising is more successful than text advertising.
4. What advice would you give to an aspiring domainer/entrepreneur/developer etc? Do you encourage the taking of risks?
Take risks registering in small amounts; avoid risks in buying from sellers and the aftermarket, as you'll almost always pay too much. Don't expect to make a fortune overnight or with one name. You'll be better without that three-word .biz. Don't listen to your gut; find evidence that a domain you're buying or registering is worth picking up to either develop or resell. Be realistic. .COM is king; .ORG is very good in many cases. .NET usually tells your visitors "I registered the .net version of this name because the .com was taken".
Don't cut into your personal savings. I made this mistake, and I still regret it. Set money aside for domaining, and be strict about spending. Don't get carried away.
5. If you were in your late-teens/early twenties*, facing the industry as it is now, would you still get involved? What would your first move be?
Absolutely. Start with just one site. Do it with something you're passionate about. Learn about search engine optimization and get the word out about your site. Throw some ads on the page, and rake in a few dollars a week. Find ways your site can earn money without the help of outside advertisers, as PPC is on its way out. Be innovative, and try to create valuable informative sites or unique, useful sites. Image hosts and "mini-sites" aren't worth your or your visitors' time. Build up some cash, read about what will likely gain popularity in the future, and be a savvy buyer.
At the end of the day, constant, expected revenue from a developed site is more reliable and worthwhile than trying to buy and sell undeveloped names.