Not any specific one, but I was a huge fan of Frank Jacobs, I guess he wrote the plurality of the song parodies for MAD, Sam Hart, a few others, but that was also where I was first exposed to the art form of song parodies.
I tend to enunciate pretty well. It's always seemed that my voice is one of those voices that people can recognize pretty easily - which has been a bit of a drawback for some characters because you're supposed to lose yourself in the character, but sometimes people look at a character and go "Oh, it's 'Weird Al.'"
Many years ago I found out something about hamburgers that really grossed me out. You may not know this, so I hope I don’t make you sick, but it turns out hamburgers are actually made out of dead cows. I am not making this up. Needless to say, as soon as I discovered that, I gave up meat entirely.
In fact, when I come up with an idea for a parody I try to resist the urge to Google the idea to see if someone has done it already because the answer is almost always, "Yes, of course they have, they've thought of it!"
At this point I've got a bit of a track record. So people realize that when 'Weird Al' wants to go parody, it's not meant to make them look bad... it's meant to be a tribute.
I write and write and write, and then I edit it down to the parts that I think are amusing, or that help the storyline, or I'll write a notebook full of ideas of anecdotes or story points, and then I'll try and arrange them in a way that they would tell a semi-cohesive story.