I am not a gambling person, but I would be prepared to put a small wager on the fact the phrase my fellow United Ghosts most often hear from prospective authors is: Everyone tells me I should write a book. In fact, if you are scanning this website with a view to writing one, it’s probably something you’ve heard once or twice yourself.

I’m not knocking it. After all, writing books is my bread and butter, so it is a marriage made in heaven. However, I am also very keen to write books that will sell.

Let me say from the outset: whether a book sells well or not makes no difference to my fee. I am paid a flat rate for writing books and do not insist on a royalty agreement as a matter of course. It is purely and simply that if someone pays me to ghost a book, I would like to see it become a commercial success and for the author to recoup as much of their costs as possible. Thus, when I first speak to any new author, I do my utmost to explore whether or not their idea is one that is worth spending time and money on.

It is a brutal truth, but with thousands upon thousands of books being published each year, it doesn’t matter how interesting your friends and family think your story is: it has to be head and shoulders above the rest to stand a chance.

So how do you really know if your book idea is good enough?

In truth, no one truly knows. There is no sure fire way of predicting a bestseller. In my own experience I have seen books I thought would be a guaranteed success only for them to achieve mediocre sales. Others that I have taken a leap of faith on have turned out to be unexpected hits.

There are, however, some basic tests you can do when weighing up your book idea.

When I am approached by authors I always try to visualise their idea as a fully formed book, nestling among the thousands of others on Amazon or in Waterstones. Is it the sort of thing people are reading at the moment? Or, is there too much competition in the particular genre right now?

If you’d like to check out the potential for your book idea in a particular genre, it is easy to find the answers on Amazon. Search for similar titles. Once you find books that are a lot like your idea, scroll down to the section titled ‘Product details’ where you will find its Amazon bestseller’s rank, overall and by category. This gives a really helpful indication of appetite for that particular style of book.

You may do a search and decide there is zero competition for your book subject. However, before leaping to the conclusion that you and your friends were entirely vindicated about your publishing genius, you should probably stop and consider why that is. Zero competition may mean there is simply no interest in the type of book you are considering. In other words, the potential for making money from it is not high. In fact, it is almost worse than if there is lots of competition which adds up to the same thing.

It is a bit of a balancing act, since book tastes do seem to go in waves. Remember all the Fifty Shades imitators? The trick is to get ahead of the pack and not to jump into the zeitgeist just as it begins to fade.

If you are still convinced your idea is a goer and want to speak with a ghost for a second opinion, it really helps if you have organised your thoughts first and can give a coherent summary of the key angles of the book. ‘It is all about my life’, is not very helpful when I am trying to see if it is a winning concept. What are the important events of your life that make you so interesting? Who are the other key players? Does it have a happy ending? Indeed, does it have an ending at all? There is little point approaching a ghost to write an angry book on your lengthy legal tussle, if there is no end in sight. It’ll be too hot for a publisher to handle and the book won’t be finished until the case is resolved. Even then, it will leave the author (and the ghost!) very vulnerable to a legal come back.

If it is a business book, a ghost will need to know about the author’s credentials to write their book. What is it that makes them the expert in their field and will get people lining up to buy their pearls of wisdom?

If anyone has a burning desire to write a book (or get one ghosted) I would always be encouraging. It might be that the initial idea, or angle, needs tweaking to make it a commercial success. A little research and thought beforehand will go a long way to making sure it is the best product it can be and something you, your friends and family can be really proud to read.

Teena Lyons writes a weekly blog on ghostwriting on her website www.professionalghost.com