My ideas for writing come from all over: a song, a performance, a picture, something someone says in passing. The idea usually starts with a situation, but occasionally a character shows up first.
When I'm first developing a story, I usually prefer it to be quiet, but once I'm into it (have a basic outline and list of characters), I often work better with some background noise. That could be either music or t.v. If it's t.v. it has to be something that I've seen before, so that I don't get too caught up in it. If it's music, it's typically folk/rock like Matt Nathanson or Frank Turner.
When I start a story I usually brainstorm on paper, coming up with locations, characters, themes, and other details that could be key to the story. After I have all of that narrowed down I come up with character profiles. I try to have an actual, physical piece of paper for each character that I can easily refer back to as needed. I've also started using Trello and Pinterest. Both can be accessed on my laptop, iPad, and phone, which makes it easy to add ideas if something hits me when I'm in the middle of grocery shopping (Trello especially).
I don't plan the entire story out before I start writing. In fact, many times I have no idea how things will end (though I can't imagine writing anything other than a happily ever after). I get the basics down and just start to write. I supposed that might change if I ever decide to do a series, but even then I'm not sure I could work that way. I find that too much planning limits my creativity, and I find myself trying to fit things in that I thought might be necessary, but in actuality are not.
I like the process of writing, of bringing something to life from nothing. Hopefully, other people will enjoy the result.