Amiable? The Artwork and Fan Fiction peeps? You've been royally screwed!
Just kidding, welcome to the forums.

As for your questions, I suggest reading the guides for starting out RPing. Such as this: http://www.gamesas.com/topic/747418-so-you-think-you-can-rp/
Now, let's see if I can answer the question with my subjective approach.
Q: What was your first successful Role-Playing character?
A: All my characters so far have been "successful", in the sense that I personally liked them. I don't know if others liked them, but that is not the point. The point is to find a character you feel connected to the most. I've been an Orc warrior, an Orc blacksmith, a Breton pirate, a Breton acrobat and most recently a Khajiit which I haven't RP'd with yet. Currently tunning the smith, the acrobat and the khajiit at the same time in three different RP's. I like all of the characters, however I'm unsure if I like the khajiit or not. It's different from anything I've RP'd before, so I've got to research on the way of speaking and such to truly be a Khajiit.
Q;: How did you come about creating them?
A: I like creating character-sheets, a lot. Every single char-sheet I've made has been built from nothing and finished in about half an hour. It's a very spontaneous way of creating a character, without too much thinking. Not sure how others create their characters though.
Q: What is your favorite kind of Role-Play setting or format?
A: The small adventure RP's with normal people (not demi-god warriors in daedric armor) is the most fun.
Q: How does one go about creating a mood without giving too much information?
A: Sorry, I don't understand the question...

Remember to watch out for the mudcrabs now, mmkay?