My ‘second rule of writing’ wot I made up myself on some long train journey, is ‘Always entertain.’ This is a simplified version of the note I originally jotted down, which was, ‘Your first duty is to this moment now.’ That is, 99% of writing is about what’s on the page NOW.
Reading a draft of a work-in-progress, you will often find a duller passage and try your best to justify it. Usually it’s for exposition purposes. ‘Oh, this has to be here to set up what will happen on page 138.’ Sorry, no-one cares about that. Your job is entertaining the reader now, not in some distant chapter that they’ll probably never reach. In other words, if you do have a vital piece of exposition, try to turn it into drama (or humour) in its own right. This can also have the added effect of disguising the exposition, so that the reader doesn’t necessarily think, ‘Aha, he’s building to something.’ Cheap wrapping paper is see-through; good quality wrapping paper looks as good as the gift.