The best way is always to stop when you are going good and when you know what will happen next. If you do that every day … you will never be stuck. Always stop while you are going good and don’t think about it or worry about it until you start to write the next day. That way your subconscious will work on it all the time. But if you think about it consciously or worry about it you will kill it and your brain will be tired before you start.(quote from Ernest Hemingway on Writing, courtesy of WriteToDone and Lifehacker)
I've tried that a few times, stopping mid-sentence a few times. The only problem I've seen with it is I forget how I wanted to continue the sentence. I'm debating about even making some notes to myself on where I'm headed.
What do you do to keep the words flowing?