The following tips pertain to novelists querying literary agents.
Things you can leave out of your query (because they are rightly assumed):
1. That your manuscript is complete. If you haven't finished the novel, then you shouldn't be querying. Period.
2. That you are seeking representation from the agent addressed in the letter. That's like walking up to the counter at McDonald's and prefacing your order with, "I'm here because I'm hungry and eating your food will make me not hungry anymore. Since I can't approach the cooks back there, could you act as a go-between for me?"
Counter girl: *blinks*
3. A one-sentence (or longer) description of your novel immediately following the 2-3 paragraph summary. Rather than emphasize your pitch, this usually detracts from the tension you've built up in the preceding paragraphs. And it tells the agent nothing new, so, in my opinion, it's a bit insulting. Like saying, "just in case you didn't grasp what I just told you, here's the gist of it in simpler terms."
For a perfect example of what I mean, click here and skim down to the title of the novel in all caps. Read that paragraph and the first two sentences of Janet's comments that follow (in blue).
Things you should include in your query (because they will make a good impression):
1. Comparative titles. This shows you know the current market and, more importantly, where your work fits in the market--you know your target audience. It also shows that you read the types of novels you write. You don't have to say your novel is exactly like these titles, just that they're similar in tone, content, style, etc.
2. A specific reason you're querying this agent for this novel. Even if it's a newer agent who doesn't have a sales record established yet, there has to be a reason you selected this person from the masses. What was it? Be honest.
3. Clean writing (no misspelled words, punctuation errors, grammar issues, etc). Yes, this can mean a pass instead of a request if you let it slip. Don't believe me? Click here.
Those of you who have been through the query process before (or are currently going through it), what would you add to either of these lists?