A lot of good
specific advice, here. Yesterday all I could think to say was
write write write, and get better every time. Pretty much giving advice Mr. Miyagi style.
Some specific things that have serve me well —
Keep your narrative
tight. Keep track of every character you ever introduced, and every possession they have. You would be surprised at the unexpected escapes you already gave your characters from a seemingly inescapable problem, about which you forgot long ago.
If you need to
add an escape to a problem, also go back and
add the key to doing so beforehand.
Use
everything you have shown. 'They' say, "if you have a gun on the wall in act one, you'd better have fired it by act three." Take that further. Use the gun, the ring, the jacket, the painting... don't call attention to something if it doesn't turn out later to be important. When I describe a room in a dream, it so that you realize five hundred pages later the same room shows up in the waking world.
To do this, you need to keep
extensive notes — about where you plan to go, what you've already finished — and read your notes for the full arc of the story, beginning to end, throughout the project, so you can keep track of your place in the story in relation to the full arc, not just what you have yet to reach. I try hard to tie the current state of the story to where it's
been, as much as where it's
going.
If you are out about town, and hear someone say something absolutely crazy, or you have an amazing idea, stop
everything you are doing, and write it down
immediately.