If your novel becomes a series, bear in mind that not all readers will start with book one. Describe your characters again and recap key plot elements. Loyal readers will appreciate the refresher.
Probably the biggest author faux pas is leaving a reader feeling lost, which also tends to throw them out of the story. If they have to stop and backtrack (which is especially difficult and annoying when you’re reading an ebook), it may be because they forgot or it could be you didn’t state it clearly enough. If a reader starts with book two or three of a series, this is especially likely to happen if you don’t do an instant replay of key events in a previous book.
Even those who have read the stories in sequence can use a refresher. It’s highly unlikely that you are the only author they read. Thus, they have probably read other stories between them, especially if a span of time elapsed before the next book was released. They will likewise be more comfortable with the story with a few reminders.