Getting started is the most important step! Pick up the phone! No, really . . . pick up the phone and call people that you've always wanted to talk to. They may not even be directly invested in the topic of your podcast but you can ask them if they know anyone who is. So what if people don't really use or answer their phones anymore. That's how you'll stand out because, really, people should use their phones more often for communicating. Plus, you'll want to hear this persons voice, right? The voice of this person you know that you've always wanted to talk to more because you met them at a party, or saw them speak somewhere, even just on YouTube. That's what reporters have to do everyday, call people they don't know, and request interviews. If calls don't work, then email, then text, then messenger. It's hard to know what someone's main source of communication is so you'll kind of have to master all of them. You'll get ghosted A-LOT, but if you are prepared not to take that personally, then you'll be fine. Most of the time, ghosters are just not wanting to tell you no, at least, that's my excuse. And don't give up too easy.
Facebook groups are another great source to find people who want to talk about stuff. Just be careful of the people who want to sell you stuff.
Figure out the how. How to do the interview is something you can figure out before the initial contact, or, I like to see what works best for everybody during this day and age. I'm pretty fluid when it comes to doing interviews in person, by phone, by skype, or by zoom. It's pretty easy to figure those things out and even easier to record your interview online. I hear a lot of people used to complain about the quality of the audio over zoom and skype, but that's changed so much since the reason we all are stuck at home these days. I don't know if people are just getting used to hearing this audio quality so they don't complain as much, or if those services have improved their product. It's probably a little of both.
There are plenty of apps for recording phone calls available. I use Tape-A-Call and it works as good as your phone signal sounds. Just make sure you are in a good area for the call. I tried to do an interview on my lunch break from inside an office building and learned that lesson the hard way. To create a pleasurable listening experience with your podcast, capture good audio. Sometimes, there isn't enough noise reduction processes in the world to make a bad phone call sound good.
I've been doing interviews for over thirty-years and the thing that has served me the best is, to not talk very much to the guest before the interview starts. I can't stand it when I hear a great sound bite and we aren't rolling yet. Hey, can you say that again in about 3 minutes? But you do your research, as much as you can, before the interview. I just google the crap out of the person or topic for an hour with a note pad and I jot down ideas of questions. You will have to talk to them beforehand and let them know what to expect. If you have prepared questions, it's okay to even email them to them. Sometimes people request this, but you don't necessarily have to.
The second most important thing after getting started, is to listen. Be mindful of your reactions and try not to verbally agree too much. Be natural, be yourself, but you don't need to say uh-huh, okay, and yes to let the other person know that your listening. It's great if you are face-to-face because then you can nod, but otherwise, try not to. And don't be afraid of silence. I love silence after something profound is said. Do a mic drop moment every chance you get! Let it sink in and then move on.
I recently experienced 15-minutes of fame, when I saw a young man with a rifle wearing tactical gear at a Walmart; it was traumatic. My reporter mode kicked in and I pulled out my phone to record his surrender to police. I was able shut down emotions while scheduling 20 interviews to appear on morning shows all over the world because of the video. You say the same thing over and over again until it starts to make sense. If this is the first time your guest has talked about a topic, they are still putting the story together in their head. If you can't do much research on your interviewee, help them find the story. You can parrot what they've said to make sure that's what they meant and that we're all understanding it correctly. but don't put words in their mouth. You can always have your trusty editor take out the parroting, after they find their voice or if it's too much.
So get started, listen and let the stories be told, let the emotions come out for you, the interviewee, and the listener. Good or bad, happy or sad, emotion is one of the finest things to come out of podcasts.