Search ReSearch blog where he posts interesting search challenges designed to help readers become better web researchers. His forthcoming book, The Joy of Search, is sure to be excellent too. If you're not familiar with Dan's work or you are and you want to learn more search techniques, check out this video that he recently posted on his YouTube channel.
Diving into Google: An advanced search methods tutorial is a video of a presentation that he gave at the National Geographic Society back in 2014. The strategies and techniques he covers in the presentation are as useful today as they were five years ago. The best part of the video is that because it is the recording of a live presentation, there is time for you to try some of the techniques while you're watching the video.
On a related note, here's a challenge that I created using the framework that Dan employs: In July my three-year-old daughter found this mushroom (picture below) while we were walking in the woods near our home in Paris, Maine. I initially thought that it might be a Lobster Mushroom but it didn't look quite right so I took a picture of it with my phone so that I could look it up later. What kind of mushroom is it? (I'll post the answer later this week).