- It's quality, not quantity: Some hosts seem to be in a race to produce as many podcasts as they can before they die, but as of this writing, Garlin has produced only six shows, and Baldwin has done only 38 since October 2011--about one every two weeks. It's much better to do fewer but better shows, than to stay on an aggressive schedule and produce a bunch of mediocre shows with a gem here and there.
- It's the guests, stupid: No matter how good an interviewer is, what matters are the guests. You can only talk to yourself for so long before the audience gets bored. For their part, Garlin and Baldwin get great guests.
- Book guests that you like: If you're interviewing someone that you don't like, respect or care about, your audience can hear it in the interview. Some hosts go after big-name guests, under the assumption that famous guests will draw an audience, but then the interviews turn out poorly. The chemistry between the host and guest is far more important than the guest's fame or status.
- Leave the audience wanting more, not wanting to change the channel: Podcasts seem to have gotten longer and longer over time--80 minutes isn't unusual, and some can run for two hours. It's impossible for most hosts to maintain an interesting conversation for that long, so some introduce games, contests, etc., which for most listeners is the signal to turn off the podcast. In my opinion, 45 minutes to an hour is a good length for a podcast; no show should be longer than 80 minutes. If you really, truly have enough material to go longer, make the remainder of the podcast into a bonus episode.
- Consider building a "company" of recurring guests: In the early days of U.S. late-night television talk shows, before most guests came on to promote their latest movie or television show, Steve Allen, Jack Paar, Johnny Carson and Dick Cavett had recurring guests, such as Norman Mailer, Truman Capote and Groucho Marx. These guests were such great conversationalists and had so many stories that they entertained audiences for years, even without new books or movies.
- Don't supplicate yourself to guests: It's easy to turn into a "fanboy" when you interview a guest who you admire, but sometimes, it's uncomfortable for both the guest and the audience. It's fine to tell the guest that you're a fan of their work before you start recording, but once the interview begins, you and your guest are equals. That's what your audience, and most guests, expect. (On the other hand, if a guest expects you to "kiss up" to them during the interview, that's likely to turn into compelling audio when you confound their expectations. An interview that goes badly can sometimes be exciting and edgy for your audience--remember David Letterman's classic interview with Joaquin Phoenix.)
- Don't be afraid to dump an interview: Even the best interviews have to dump an interview from time to time. Perhaps you or your guest is having a bad day, or you get into an interview and realize that there's absolutely no chemistry between you and the guest. If you record an interview and after listening to it find that there's no way to cut it into a usable form, it's no sin to say "Sorry, I was having a bad day, and we can't send the interview out." It's better to kill a bad interview than to air it and disappoint your listeners (unless its very badness makes it funny or compelling, as in the previous bullet point.)
If you follow these rules (and are a good interviewer to begin with,) your podcasts have a much greater chance for success.