About your recording environment
The reason that these presenters all fail is, at its heart, because they are making video and they are using, basically, webcams. This drives decisions as to the placing of microphones. So they use microphones designed to be used relatively close to the face but, because they want to be seen, they keep the microphone out of sight.
That makes them
a) shout at the microphone to get level; and
b) the mic pics up the sound void in the space between the mic and the mouth which leaves it sounding as if the speaker is in another room.
When you are making an audiocast, you don't have that restriction. You can position the mic where it should be to "hear you" properly. But when it comes to using a room as a studio, "space" is a very important factor.
When it comes to your studio, there is one golden rule: the terrible triplets of echo, reverberation and presence are your enemy.
But equally, you don't need to aim for a completely acoustically dead environment.
I have built what I call a "study-o" which doubles as a studio and a study. The walls are lined with floor to ceiling bookcases. The windows have mesh roller blinds. The computer and other tech live in a "tech shed" with a door I can close while I'm recording so minimising fan, etc. noise.
I could turn the PC off as I don't record into it but... I use it as a teleprompter for my script :)
My desk, which is the recording booth, was designed to have sound baffles all around. But I haven't fitted them.
There is something to consider if your podcast is intended to be a bit chatty, to draw the listener in, then it's possible to be too perfect. An odd car horn, the sound of a cup being put onto the table or child asking if you want a cup of tea humanise your production.
Because of this, I have deliberately left a bit of the "recording in the toilet" sound in my carefully designed set up, precisely so that it doesn't sound like I've gone back to the old days of recording in a proper studio with an engineer and a producer.
But if you are working, as I do, into a enclosed space and it is too "echoey" there are some very cheap things you can do . The first is to get some expanding curtain rails (e.g. for shower curtains. Put them up and hang fabric from them.
Here's a science bit: there are three states of matter: solid, liquid and gas. Once matter is no longer solid then it follows the same principles of fluidity and ability to permeate. So, the more absorbent to e.g. water a material is, the more it is going to absorb sound.
Do you see where I'm going with this? What do you think is the simplest, cheapest and the most quick and dirty fix ? Hang your most absorbent towels on the rail. And when you are done, put them back in the airing cupboard!
In the old days, we used to have perforated hardboard all over the walls. Then we got fabric panels and later highly specialised acoustic foam. But home studios used by musicians used paper egg trays. In fact, I have a stack of them in the corner of my room now, wondering whether to bother with them. They would line my cubicle and be obscured by a piece of nice fabric.
Pretty much everyone I know has give up with the idea of a large shield placed on the desk. Even my son, a professional musician, has stopped using one because its too much like wearing a blindfold.
The single most effective thing you can do is none of these : it's to put foam cones in the corners of your room. You can make your own or buy some very cheaply on-line. But they aren't pretty.
When you say the word "pop", the "p" sounds make a popping sound. So do lots of other letters. And then there's the sound of outgoing breath. For this reason, "pop" filters are popular. Whether you really need one depends on all the factors we've talked about before, your choice of mic and its position being paramount.
My SoundRocket doesn't need it : it has a sponge "sock" and that's good enough. There is no hard and fast rule: don't use one because you think it looks professional or because you've seen others using it - use it if it makes a material, positive, difference. Mostly, given the nature of your recording as a mono, speech only, audiocast you probably don't need it.
Having said that, although the screen is called a "pop filter" it also has another purpose: to reduce the effect of sibilants : these are the swooshing sounds that accompany the pronunciation of "s" and, not quite he same but similar, "f".
This is my own biggest problem and I know that it results from the way I hold my mouth because, if I concentrate on how I speak, I can avoid it. But that's not easy when you are concentrating on what you are saying. I have tried using a filter but have concluded that, so long as it's not obtrusive, it can stay.