I've come to realise that my best work, where short fiction is concerned, is that which rushes out in one sitting. If I'm not engaged enough with a story to finish writing it, I figure nobody is going to be interested enough to finish reading it.

So, I have a (computer) folder containing about 100 files. Everything from ideas to 6000 word stories needing a polish. When I'm stuck I troll through these files until I get an idea - usually completely unrelated to what I'm reading.

As a submissions reader for an SF magazine I get to see a lot of fiction which isn't ready for publication, and when I see the same flaws in my own stuff (indifferent story, lack of an ending, characters the reader doesn't care about, etc) I slip it back into the 'later' folder.

In terms of finishing my novels, deadlines concentrate the mind wonderfully. I can procrastinate for several months, then blow gaskets getting everything done in a three week spree. I also use a program which splits my novels into chapters and scenes, making it easy to leap over the boring bits to get to the stuff I feel like writing at the time.