At what point, as a first time author, should you start looking for an agent? I imagine a good general point would be "when your book is done," but should you get an agent before or after sending your work out to publishers?
I strongly recommend before - it's extremely rare these days that a first-time author gets anywhere without an agent, to the point where it's simply ridiculous. Getting an agent is difficult enough, but if you're fortunate enough to get one (could happen), then you know that your manuscript is of some worth, at least, and it'll be much easier to find a publisher. Obviously, though, it depends on the reputation of the agent and publisher: if the agent is well known and the publishing house in question is not, then you're far more likely to get published, and vice versa.
If you've sent your book to the publishers, who would the agent send it to? And as for sending it out when you finish that first novel, you're dreaming, unless you've taken meaningful steps to make your writing (not the plot, but the writing) better then the thousand other people in competition with your title. In the real world of publishing, if the one reading your work can tell it's not written by a pro your audition is over. Here's the thing. Finishing is just the first hurdle. Adding sparkle, making your dialog pop, and all the other things that differentiate the pro from the amateur matter a great deal. Certainly, you stand as good a chance as any other writer, but it's not a matter of luck, chance, or a gift from a benign deity. As they say, success is 1% inspiration and 99% perspiration. So before you send that book to a publisher or an agent, be certain you've made it as good as your talent and craft can make it, because the publishers have plenty of "just as good as" writers. What they're seeking is the "Oh my god this is good," writer.
If the goal is getting an agent, don't submit to publishers on your own. It's not necessarily true that getting an offer from a publisher will guarantee you an agent. And the places you'd want to submit to first are not places you can access without an agent. Yes, I know opinions vary on that subject, and some people tell you to ignore the submissions guidelines and submit anyway, but I don't think that's a wise move. Whatever your goals, I wish you good luck!
...yes... but 'done' as in edited and polished to a faretheewell... ...when you have an agent, you don't send anything to publishers... that's what the agent does... ...if your book is a novel, you'll have a much better chance to see it published if you have an agent... with some non-fiction, you may be able to get a publisher on your own, but it's still better to have an agent find the best publisher and negotiate the best deal for you... ...if you submit directly to publishers and one or more show interest in your book, you may then be more attractive to agents, so can query them and mention the publishers that are nibbling... then if an agent takes you on, they can make sure you get the best deal...
FWIW, I've seen this backfire so many times. Agent turn down authors with offers in hand all the time. So you have this author running around trying to get an agent while a publisher is waiting on a reply, getting annoyed. I've even seen a publisher drop an author b/c they took too long to reply to their offer (because the agents they were contacting were still rejecting them).
a valid point... but i certainly didn't mean the author should delay signing with the publisher too long, only that s/he could make good use of the time allowed to consider the offer...