Lots of new writers want to tell potential agents about all the books they’ve written, even though they cannot say they have sold any. The point they’re trying to make is that they’ve paid their dues. Instead they come off looking like losers. Giving the agent the excuse she/he is looking for - a valid reason to say no.
There are two things you must never forget about the species known as homo sapiens agentimus. The first is that they have developed huge egos necessitated by the fact that they spend much of their working life being told no (agents these days are likely to be selling some thirty percent or less of what they take on). The second is like unto the first: They don’t want to take on anything unless they can convince themselves they are sure to sell it, even though they know full well they probably will not.
So (insert Your Name) has done a romance, a western, a SF book, and not one has been published? Now I’m being offered this piece of literary fiction? What does this yo-yo take me for? The last hope of the no hopers? Where’s that pre-printed card, the one that says we’re not taking on any new clients… Ah, here’s the one that says we’re not the right agency for this project. That will do.
Score another ding on the submissions spreadsheet.
What the agent wants to hear is how you woke one morning and this entire book was laid out before you, as if it were an infusion of knowledge from the Holy Spirit, Athena (or was it Venus?) springing toga and all from the forehead of Zeus. And you sat down and wrote 110,000 words in one week without stopping to sleep. And now you come bearing this treasure to the agent who sold (insert the title of a book sort of like yours) and who has shown herself/himself so utterly brilliant at making sure the primary publisher doesn’t muscle in on the sub-rights action, while managing to put together six figure deals on his/her three most recent sales… Yada, yada, yada.
Except that the last part really isn’t as silly as it sounds. You genuinely should make the agent understand that you’ve done more than the usual amount of homework. Due dilligence as it were. And that for your part you understand this is a business relationship and the agent’s job is to be a rainmaker.
The creative hooey is about recognizing that if you’re a published author you begin your approach with a list of titles and publishers. If you are not, it’s better to be a virgin.
Only one caveat: Never go to an agent with a ms that has already been shopped around without being absolutely honest and upfront about the fact. You’ll be blackballed otherwise. And you’ll deserve it.