Similar to the pre-search needed to select your career idol, I also recommend doing a little pre-searching before choosing an industry trend. If you're not sure what you would like to focus on, take a look at a few news sites such Google News or Reuters. Search for a topic of your choice and see what's making headlines.
Look at my example below. I am a huge fan of podcasts. After conducting a search using the keyword "podcast" on the Google News site, I retrieved a list of articles to review. The article about movies being turned in podcasts stood out to me. From here, I can search for articles on that topic to see if this is indeed an industry trend for podcasts.
In addition to checking news aggregators, check out industry associations and publications. You can often find associations by using it as a keyword in your search along with the name of the industry.
For instance, my search terms "film director association" retrieved websites for the Directors Guild Foundation and the Motion Picture Association. You could use these websites for industry news and resources that may help you further explore your trend.
Similar to the search we did with associations, we can do the same to find publications. Add the word "publication" after your industry trend to retrieve a list of sources that may provide more information on your topic.