1. Make a list of each character and the situations they've faced throughout the story. This is a methodical way to avoid forgetting a loose end you really should tie up at the end. HOW TO WRITE A STORY ENDING
2. Decide how you want to wrap up a situation for each character. In a romance this might be sending the characters out on a first date as a way to give them a happy ending. Find a similar solution for each of your minor characters, if it's appropriate to do so.
3. Look at each of the main characters and decide how you want their story to end. A good ending is one where all the conflicts are resolved and all misunderstandings are straightened out.
4. Put your main characters in a position where they have to deal with each other. This gives them the opportunity to resolve any conflicts or misunderstandings. They can be locked in an elevator, stuck on a boat or any other situation you can conceive where they're forced to talk.
5. End the story you're writing by allowing your main characters continue their lives either happily together or comfortably apart. Since most readers prefer a happy ending, many characters end up happily together.