Unsolicited manuscripts if accepted by publishers are placed in a slush pile, which a publisher's readers sift through for quality to refer to acquisitions editors for review [In some cases with smaller publishers the acquisition editors does it all]. After a final sort the best goes to the editorial staff. Unsolicited submissions have a very low rate of acceptance, possibly at the rate of three out of every ten thousand[Loosely based on a given statistic].
The statistic is that 0.03 percent of all manuscripts submitted to publishers in the US each year are published. Meaning: out of 10,000 manuscripts submitted, only 3 are published. [Remember in most cases submissions are not direct but through an agent.]
In the mid 90s in a given year, in all genres and categories, approximately 80,000 [at 0.03% Exceeds 250,000,000* submitted] titles were published.
In science fiction and fantasy (SF/Fantasy), approximately 1600(exceeds 5,000,000* submissions at 0.03%) novels were published by all SF/Fantasy publishing houses combined. [*These numbers are bloated because they might include republication of old books]
Of the 0.03 percent (3 out of 10,000) accepted for publication, 9 out of every 10 fails to pay back production costs.
A very rough breakdown of costs might look like this.
• 20% Royalties, rights, permissions
• 25% Editorial, Administrative, and other associated costs
• 30% Production, Paper, printing, and binding
• 25% Sales, marketing, Warehousing
It becomes easier to see why "One trend in publishing is to try to bring out fewer but bigger books."
Many aspiring writers don't publish because their work is substandard compared to other writers. However, some writers don't get published because, even though their work is good or even brilliant, there's not enough market for those ideas. The market caps before all submissions run out.
-----Keeping in mind that many of the submissions come from agents and not all will be published and they do their own sorting before the publisher sorts their choices.----
Before considering getting an agent: consider:
1) publish short stories to acquire recognition,[this is not possible with some genre] or
2) write a novel, submit to a publisher for review; when a contract is offered, call an agent.
Most agents have a declared response time of three months for queries, however most are inundated with queries and manuscripts, and that might extend to six or nine months.[If you hear nothing and submit again; wait 6 mos and resubmit as though it's the first time.]
Having an agent can't guarantee you'll get published. Writing a great manuscript is not, in fact, a guarantee of getting published. It's the editor, not the agent, who purchases the manuscript. The agent works the market based on trends.
Once published with decent sales numbers, and a track record, you may want to move on to a better or more powerful agent for your budding career.
I'm not necessarily endorsing Self-Publishing; this is just food for thought.
J.L. Dobias