They could fill books with what I don't know. (They have, actually, and they're at the library. I will go check some of them out as soon as I finish this post.)
I do pride myself on learning quickly. I can and have made the newbiest of newbie mistakes, but I know I have a steep and steady learning curve.
The first time I queried, lo many months ago (February of 2010, to be precise) I made several errors. One was going through websites like query tracker and finding every agent that covered my genres of interest.
Now, that's not a bad thing, I still think that's a good start, but at the time, that was all I did. I put those names in a spreadsheet, I read directions for what each one wanted, and I started querying.
I wasn't a horrible offender.
I didn't send a group email to twenty addresses with the opener "Dear Agent".
I didn't refuse to write an honest to goodness query letter.
I followed directions.
I acted professionally.
I thanked authors who sent me advice or suggestions, but I didn't clog the in-boxes of those not interested with multiple follow up emails.
But if you had asked me WHY I'd picked the agents I was picking, outside of genre of representation, I'm not sure I could have answered that question. At the time, I didn't know HOW to find out more specific information about agents, if they didn't readily provide that information on their blogs.
To be perfectly honest, I didn't take the time. I thought, "the agent that likes my book is the right agent for me."
More recently, I geared up to query again, and as I prepared, I challenged myself to say why.
Why would I want to work with this agent?
Why do I think they would be a good fit for me?
I'm not saying there was a mind-blowing-we-are-cosmically-destined-to-be-agent-author response for every one, but I felt I HAD to answer the question of why, if only for myself.
The website Literary Rambles' agent spotlight series proved INVALUABLE to me this time, in delineating from agents who (as far as I could tell) were a good match as opposed to those who were not.
Of course, for some agents you can get a better feel for what they like and how well you mesh based on their online personas. Others do not have a cache of articles, comments, blogs, and tweets that can give you insight into their tastes and personalities.
I'm not saying it's always easy, but I do think it's worth it.
Do you challenge yourself to answer the why question?
How do you decide an agent might be a good candidate for querying?
Do you read their tweets? Their blogs? Have you ever found that alters your desire to be repped by a given agent?