The "Things I've Been Asked Lately" series of posts (TIBAL) is exactly what it sounds like. People ask me questions in real life, on the blog, or on the forums I follow and I endeavor to do my best to answer them.
How Many Submissions Should I Have Out At Once?
This is a two-parter. I started off answering this about short fiction but then was informed: But I was really asking about novel submissions. How many of those should I have out at once?
As many as you can handle responsibly.
When you put a novel on submission you first have to query an agent about your project. When the agent responds back, she'll either ask to see a partial manuscript (approximately the first three chapters), the full manuscript (the completed novel in its entirety), or she'll send you a polite rejection. If more than one agent requests part or all of your manuscript then by all means send it to all of them! If one of them requests an exclusive look at your manuscript (see an agent's view of that little sign of weakness) tell them they can look at it but it's already out with other agents.
Now let me get back to that phrase "as many ans you can handle responsibly."
You must first query an agent. Being responsible means that you take the time to write a nice query letter, that you follow letter writing conventions, that you follow the agent's guidelines as to what they want to see in a query.
Being responsible means you MUST query them one at a time. Do not create the world's longest CC list of agent emails and hit send -- these emails are almost always deleted.
Being responsible means you address it to a person not "whom it may concern."
Being responsible means you've checked the agent's guidelines and you know they are interested in acquiring your genre of writing (or something particularly close to your genre if you sit on a "cross genre" area, for example, if you write steampunk and but the agent says they acquire fantasy and sci-fi, then it's reasonable that they'll at least look at a sub-genre like steampunk).
Most agents claim to respond to query letters in a week's time or less. This means that you can have out as many query letters as you feel comfortable with -- maybe one Saturday you scout out and email a handful of agents, like four -- and during the next week you'll likely hear back from all of them.
If all of them reply 'no' is it time to get discouraged? Hell no. That was only four people! While waiting to hear back from those four it's perfectly fine to be researching the next four agents you'll submit to. Actually, it's probably healthier to be researching new agents rather than becoming fixated on the ones you've yet to hear back from.
Tomorrow I'll tackle the same question but for short fiction submissions to magazines.