Mention anything you have had published
If people had enough faith in your writing to publish it, then this will grab attention. Even if the piece you have had published is not directly relevant, still mention it. Though it takes different skills to write an article than a story, it still illustrates a level of competency.
A word of caution: If you have had many pieces published in lots of genres, pick the most relevant one. You don't want to look like a jack-of-all-trades!
Mention any complements you have been given
What sort of positive feedback have you received? Have you won any prizes or submitted a piece for a Creative Writing course that received praise? Mention this.
A word of caution: Do not ever say that your best friend / Mum / child likes your story. Unless they are a well known critic or writer their view is likely to be highly biased, and mentioning it makes you look unprofessional.
Do you have relevant life experience?
You may not have a great deal of previous writing experience, but there may be something relevant to the genre. For example, maybe you are writing for young adults and are fairly young yourself, or maybe you are a school teacher and writing for children. If you are writing a novel based around a certain sport or profession that you have a deep knowledge of, then this will help your saleability.
A word of caution: do not fish for tenuous links. If you are writing a horse story and once rode a donkey on holiday it will make you look a bit silly, to say the least.
Make favorable comparisons
If you are writing in a genre or on a theme that has proved very popular, there is nothing wrong with mentioning this. It shows you have an awareness of current publishing.
Words of caution: Don't make yourself look like an imitator. Everyone wants to write the next Harry Potter and publishers won't be overly impressed if it looks like you are two or three years behind a trend. You also don't want to appear arrogant.
Include all essential details
If you have finished the book then make sure you say this. This will make it more likely that publishers will take a chance on a new author. Mention the genre and target market as well as the length. All these details make it easier for an agent and, in turn, a publisher to see what they are dealing with.
A word of caution: Don't lie! If your piece is only 35,000 words don't say it is a completed novel of 70,000 or you will tie yourself up in knots and may well get a bad reputation.
Do your research
It sounds obvious, but if an agent only deals with children's fiction or just horror, then don't' send a sci-fi story to them. It will just lead to disappointment and wastes your time. Invest in a Writers and Artists' Handbook for up to date contact details. There will also be submission guidelines. Follow these to the letter!
A word of caution: Having the Writers and Artists' Handbook does not make you an expert. Do not expect an agent to be impressed by information you found in it. After all, this is the absolute minimum you have to do.
Look professional
Avoid anything that would not fit with the professional image you are trying to create. If you say you are writing literary fiction, giving the email address FluffyBottom@hotmail.com will not impress. Equally, do not use lots of different fonts and colours and it is best to avoid a flashy logo you have made for yourself. You may stand out, but most probably for the wrong reasons.
Don't look pretentious
Publishers may well not be impressed by letters after your name, unless they are relevant. Your PhD in astrophysics may well be fascinating, but it does not apply to writing a comedy set in a theatre. Do not show off about things that have nothing to do with writing as it may appear you are trying to cover up for faults in your piece.
Don't mention any negatives
In fact, don't include anything that could be construed as negative. Do not say, for example, that you received negative feedback in the past and have improved. This happens to everyone, but mentioning it creates doubt in the mind of whoever reads the letter. Do not criticise other people's work as you sound rude and an agent will want to work with someone upbeat and interesting. Try to make everything you say hopeful. For example “I look forward to hearing from you” is far more active than a slightly apologetic “thank you for taking the time to read this”. Look at the title of this paragraph; “don't mention any negatives”. Don't you think “be positive” would have been better? If you noticed this yourself then you can see the importance of a positive spin.
Be unique!
What is your unique selling point? Publishers may not be interested in just another romance or another book set on Mars. While there is nothing wrong with saying your writing fits into a genre, you do not want to sound derivative. Maybe you have an unusual setting or a highly unique writing style.
A word of caution: Try not to sound like a gimmick writer
Good luck with getting published!
