Coincidence shouldn't make things easier. Sometimes you can get away with using an accidental confluence of events in a story, such as having otherwise unrelated characters be at the same place at the same time. You can get away with this in two cases. The first is when the fact of the coincidence is one of the initiating forces of the story. The second is when the coincidence makes things worse for the protagonist.
Coincidences seem contrived and false when they're used to help the character.
Remember, it's not a coincidence if it is a logical consequence of prior events in the story. Lay groundwork for your revelations. To paraphrase the last point, most events should be a logical consequence of prior events. Mysteries should not be mysterious once solved, and surprises should not be surprising in retrospect. Never withhold information the reader should know.