On average, the most crucial part of a book are the first twenty pages. The reason for this is simple; most people do not stay focused on one thing for very long. As a result, to draw readers in, an author has to create a powerful introduction to any story. Otherwise after the twenty pages, the reader will stop and most likely never get back to the story. A strong introduction for that reason is extremely important if you wish to keep the audience's interest.
There are many ways to go around making the first twenty pages interesting enough to keep the audience's interest. J.K. Rowling in the first Harry Potter book did this flawlessly by getting right into the supernatural elements of the story and then building up interest with the main character. The Death Note manga immediately introduces the death note and hints at the rivalry that will play out between Light and L. Not even three pages in The Walking Dead comics, the zombie virus is widespread in the plot. These are a few examples on how other authors have gained an audience's interest.
However, do not in any case (unless it is an editorial or review) use a prologue of any kind. Although it is supposed to be a great way to dive right into the story, truthfully it can be a death sentence for your book. No one wants to read a story before the actual plot, which at this case they have no knowledge on. There is additionally the second variant of this problem, which is over-saturation of the story. Either way, prologues can be the death of a story.
The best way to avoid prologues is simple; just get right into the story! It saves you time writing the story and the possibility of your idea not even being given a chance by anybody.
The only example of a prologue being used right I have seen is in the Warriors book series. There, the authors (four in total), make sure to add a relevant scene into these first few pages to keep the audience's attention on the plot. It works here because it goes right to the plot and quite honestly shouldn't be called a prologue in the first place. All they'll do by calling the scene the prologue is possibly lose interest from the audience.