Tips For Addressing the Mic
Different mics behave differently. Some want you close, some want you a little further. Some pick up room noises really well, while others don't. It's important to figure out your mic to know how to make your voice sound optimal. This often just takes a lot of trial and error.
Sitting vs Standing
It's something to experiment with. A lot of voice actors like to stand. Singers like to stand. Podcasters and radio hosts traditionally sit. Try doing both because you may hear a difference. For instance some people talk faster standing. Some can express their thoughts better when their hands are free to move around.
Experiment, then do what feels right.
Always Use a Pop Filter
A pop filter or wind screen or even a sock or nylons over the mic helps remove "P" sounds and from exploding the volumes. These sounds often create these sharp spikes of volume that are undesirable. The nice thing about a pop filter is that it's cheap so there's no reason not to get it.
Make Sure You're Recording
It may be helpful to make a checklist for each time you record to make sure you did everything. Close the door, silence phone, put note on front door saying "go away", and make sure the recording button is pressed. There are many horror stories of people saying they forgot to hit it.
Wear your Headphones
Some studios, especially NPR ones, make this a requirement when recording. It's because you as the producer needs to hear how the show is being recorded. This is especially true when out in the field recording people on the streets or something. Have those headphones on to make sure you're picking up their voice properly and outside noises aren't too bad. It's weird for them to talk to a person with headphones on, but you can assure them you hear them just fine through the mic.
Get Your Voice Ready
You can search YouTube for voice warmup routines. Many podcasters go through routines like this before hitting record. Find one you like and warm up your voice.
The deep traditional radio announcer voice was a thing of the past. Today unique voices are more desired. So be yourself. You are unique enough. Some people play a character of themselves on the podcast. They are more calm or pointed or scary sounding. That's fine too but you need to be consistent with it and make it a part of you. Channeling your inner scary voice is good, but channeling someone elses inner scary voice is not really a part of you and will be more challenging. To get yourself into the character, some people write out a few sentences that get them into the voice. For instance to put me in a Boston accent I might read "I pahked my cah at Havad" (I parked my car at Harvard) which resets my voice into the character. It's good to have these sentences posted on the wall and read them before hitting record to get your voice all set for the show.