PhilK:
Ideas for new stories seem to come to me quite easily. It's finding the time to get the damn things written that's the problem....
I agree- most of my stories are largely based on events, locations, and people in my life. The bits and pieces are just mixed up and disguised enough to preserve anonymity. I often find I write what I think is just a vanilla journal entry or something- a few paragraphs just to get something out of my head- and it winds up in a story a few months later.
That said, I usually start my stories by thinking of the emotional states I want to convey, then pick the characters, setting etc that will best accomplish that.
I'm too new at this to have writers block yet. I know it's coming eventually and I'm more than a little nervous. The closest I got was the difficulty in writing a Christmas story that several of the others expressed. I have more than a few failed attempts languishing on my hard drive- but maybe there are some salvageable pieces for another story.