So another way to look at ‘what are the best topics for seminars’ is … they are topics that lend themselves to being presented in a seminar style of presentation. That would seem somewhat of a circuitous answer but your topic has to work within the seminar-delivery framework. Your marketing also has to be consistent. If people register for your seminar thinking that they will learn the how to do something and have a chance to practice it and they don’t, you will have unhappy audience members.
As for actual topics for seminars, the list is likely endless. However, you have to choose one that people would want to attend. While you may be very interested in a topic, spend your time researching, practicing, promoting and marketing it, if nobody is interested, then what value is it?
Researching trending topics in the news or what people are Googling for info can be a way to come up with good topics. Who knows, you may find a topic that you will become passionate about that will open more opportunities for you.
Thanks for your question.
... as originally answered on Quora.com