Interest
If you're a doctor, lawyer, or exotic dancer then your choice of topic ic probably quite obvious. But what about the rest of us who's area of expertise may not be so obvious?
If you're thinking of doing a podcast in support of a business endeavour, then your choice of topic is also likely more obvious that the casual hobby podcaster. Regardless of the situation, it's likely that you already have some idea of what you'd like to talk about.
Hone that fuzzy list of topics down to three and then pick from the three.
Longevity and Reources
Other things to consider are longevity and resources. If you can't envison at least 6 months of shows on a given topic, then it's likely not a good fit for you. Resources also play a part. If you're thinking about doing product reviews then you have to be able to maintain a pretty steady stream of products coming in the door from manufacturers and suppliers.
