Take a pencil to write with on aeroplanes. Pens leak. But if the pencil breaks, you can’t sharpen it on the plane, because you can’t take knives with you. Therefore: take two pencils.
If both pencils break, you can do a rough sharpening job with a nail file of the metal or glass type.
Take something to write on. Paper is good. In a pinch, pieces of wood or your arm will do.
If you’re using a computer, always safeguard new text with a memory stick.
Do back exercises. Pain is distracting.
Hold the reader’s attention. (This is likely to work better if you can hold your own.) But you don’t know who the reader is, so it’s like shooting fish with a slingshot in the dark. What fascinates A will bore the pants off B.
You most likely need a thesaurus, a rudimentary grammar book, and a grip on reality. This latter means: there’s no free lunch. Writing is work. It’s also gambling. You don’t get a pension plan. Other people can help you a bit, but essentially you’re on your own. Nobody is making you do this: you chose it, so don’t whine.
You can never read your own book with the innocent anticipation that comes with that first delicious page of a new book, because you wrote the thing. You’ve been backstage. You’ve seen how the rabbits were smuggled into the hat. Therefore ask a reading friend or two to look at it before you give it to anyone in the publishing business. This friend should not be someone with whom you have a romantic relationship, unless you want to break up.
Don’t sit down in the middle of the woods. If you’re lost in the plot or blocked, retrace your steps to where you went wrong. Then take the other road. And/or change the person. Change the tense. Change the opening page.
Prayer might work. Or reading something else. Or a constant visualization of the holy grail that is the finished, published version of your resplendent book.