Coincidence in story (Patreon)

Recently in my writing I have been relying too much on coincidence or convenience to advance the plot. I plan to fix those parts before they are published, but it's easy to fall back on that.

It's not that having some amount of coincidence isn't fine, or even sometimes required, but too much becomes unbelievable. 

In terms of avoiding coincidence entirely, that basically just leaves you without a story. Certainly, there can be plans in place everywhere, but even in the case where someone has everything plotted out perfectly... not everything will be under their control. It might even be more coincidental for people to follow all of someone's predictions, even thought it isn't advertised as luck or coincidence.

We'll take an example from Harry Potter. Spoilers ahead for Chamber of Secrets, if you somehow haven't read that yet or seen the movie. You can stop reading here, I guess.

When Harry is fighting the basilisk, he pulls the sword of Godric Gryffindor (literally out of a hat) right when he needs it. Why, what an amazing coincidence! However, it's made better by the fact that there were some amounts of foreshadowing, at least that the hat is special. It wasn't like the basilisk broke a wall and revealed a sword coincidentally behind it.  Instead, it is mentioned that the sorting hat was replaced because it was very old. In stories about wizards, very old magical things are very special, so it's not too unbelievable that it might have contained a magical sword. After all, what's a sword in a hat when someone left a series of rooms and a big snake underneath the school? It's a coincidence, but it was decently handled.

I can't actually think of any particularly bad examples of coincidence off the top of my head, but they are all over the place in many stories. However, some is unavoidable, and if it's handled well doesn't detract from stories at all. That's basically all I had to ramble about on this topic.