Write well. Write often. Edit wisely.
Readers can get really ticked off when you use coincidence to solve story problems. They are pulled out of the fiction and made aware that you’ve been fooling them.
Coleridge’s willing suspension of disbelief is often quoted to explain how a reader can immerse himself in fiction and why it’s important for a writer to create believable worlds. Explore the importance of the suspension of disbelief.