From the theoretical into the practical: 1) go to guitar center and see if they have any USB microphones you can try out. Don't spend more than $150. Spend more than $50. 2) Audacity will probably work. If you've got a mac, GarageBand excels at podcasty stuff. If you're on a PC, I'm not sure what they're doing these days. 3) Sit up straight and be comfortable. You might actually find that you like your performance better standing. Either way, if it sounds good to you, it sounds great to everybody else. 4) The perfect room to record in is one with a carpet on the floor, bookcases behind you and enough furniture that it doesn't sound empty. Bonus points for curtains. 5) The more effort you throw at it the more disappointed you will be at the results. Hit the basics, recognize that perfection is not the goal, and that the voiceover spots you're attempting to emulate are run by people like me with gear like mine and I've got years and tens of thousands of dollars into it and you don't want it that badly. That said, most of the guides you can find on the internet will get you there. It amazes me that none of them talk about headphones; you want to monitor what you're recording, as you're recording it, through CLOSED CELL HEADPHONES. No earbuds, no open baskets. If you put them on your head and you can't hear the outside world as well, they're closed-cell. Again, go to guitar center and give 'em a listen. Good luck.