"I want to do a talk, but I have no idea what to talk about" might be one of the things I hear the most.
Topics for me come from my own experiences and how I've answered my own questions in learning/succeeding/fumbling/failing. For example:

Questions/Situations that arise in my day-to-day.
One of my upcoming talks is called, "Kill Your Baby, Sell Your S#!%" - This talk shares some crucial tactics specifically for designers and developers on how to let go of their work enough to completely change it, but also the art of selling their work and/or ideas to their clients or internal teams. This comes from something I find myself helping many of my design and developer team clients work through a great deal of the time and spans all the way back to what I used to teach my students of Graphic Design/Interface Design at UNLV.

Real experiences I'm having, or have worked through. Sometimes these are product design lessons learned like "Designing for Emotional Engagement". Sometimes these are life things like "Through Burnout and Back Again."

How do YOU come up with talk topics?

Note: All tips written for my #talktips #30days challenge are written in 5 minutes or less.
if you have more questions or would like more info about any of my #tinytips, leave a comment!