Ye ken, we've been robbin' and running aroound on all kinds o' worlds for a lang time, and I'll tell ye this: The universe is a lot more comp-li-cated than it looks from the ooutside.
Terry PratchettOften I sort of work up and down the manuscript. I sometimes used to go ahead of myself to see what was going to happen next, to make certain it fits what was going to be happening soon.
Terry PratchettHowever, you do need rules. Driving on the left (or the right or, in parts of Europe, on the left and the right as the mood takes you) is a rule which works, since following it means you're more likely to reach your intended rather than your final destination.
Terry Pratchett