Trickiest of all is bringing in that ending with punch, pow, wow and 'I'm sorry it's over' power that brings readers back for more, clamoring for your next book. The ending that helps get you an agent or a publisher - which helps lead to those readers.
So today I decided I'd write a bit about things you should and shouldn't do to create that nail-biting, throat-gripping ending. Of course HOW you accomplish these ideals is up to you - you're the writer - but lets clarify some of the things that will help make the ending of your novel outstanding.
First some things you SHOULD do.
Near the end is where your biggest surprises should happen. Here's where some tiny trivial detail seen earlier in the book might play a big part in the ending. Not just might, but should. Here's where that small detail the reader may well have skimmed over will pop out and be a very decisive factor in the novel's ending. Remember that pocket knife Jimmy's dad gave him for his birthday? Here's where that little knife can chisel a hole in the way and let him and his little sister escape to safety away from kidnappers. Remember the bubble gum wrapper the killer dropped on the floor when he left the scene of the murder? Here's where that wrapper can play a crucial part in the murder's apprehension. You get it. The 'Wow' factor.
Another thing you, as the writer, needs to do is to resolve the main conflict of your novel. No, I'm not telling you all your novels must be possessed of a 'happily ever after' ending, but something in your ending that's uplifting is a real boost. Readers love to be raised up a the end and remember publishers, editors and agents want to give readers what they want. So do you, actually. Here's where you put your imagination to the test.
As you write your way to the end of your novel it's also important to give your hero a chance to redeem himself. Yes, he's screwed up royally along the way, made a mess of things, been a bit of a jerk, but it's part of the 'uplifting' thing above - in the end allow your reader to know the hero has done the right thing.
Here's also where you want to be writing those loose ends together. All through the book you wrote you planted questions - yes you did. This is the place, the here and now where your writing skills need to be directed to addressing each of those questions, creating closures. Readers don't like to be left hanging so answer the questions even if it's just to say there's an issue that will be resolved after the book ends or perhaps in another book coming in the series (IF it is a series).
Those are some of the things that, as a writer, you should do. So what shouldn't you do?
Well the ending isn't the place to introduce new characters and/or subplots. Don't stick something in that hasn't been foreshadowded. It's jarring and it could well cause your readers to blow you off for future books.
The ending of your novel isn't the time to change your writer's voice or tone either. Be consistent.
Avoid writing page after page of explanation of philosophizing at the end of your book. Keep your descriptions to a minimum and focus on the conflict and it's resolution. You should have planted all sorts of goodies previous to the last 50 or so pages of your story. Now's the time to moved it along and wrap it up.