There is lots of information out there to help you write query letters. Even with all that advice, you may have a horrible query letter and not know it. So then, you need to go to other sites for help with your actual query.
Here are a few sites I have found.
Mother. Write. (Repeat.) is the blog of an aspiring writer. She has been doing a contest called The Agent’s Inbox. A limited number of people can submit a query and the “first page” of their work. Anybody can comment on your query and she has a literary agent who reviews them too. If the agent likes any of the queries, she may ask those people to send in their manuscript. The agents that she has hosted have all been well known agents and it is a great opportunity to get some feedback.
Writer, Writer, Pants on Fire (Gotta love that name) This blogger is an agented writer and writes about
writing and other things. (Lots of Ws in that last sentence.) She has offered to do critiques of queries. Although it appears she has just started doing this (I actually found her through the above blogger), I like how she is doing the critiques. She offers comments almost line by line and then summarizes what she thinks.
I have done the first one, and I’m in line to do the second one.
Query Shark is by a well-known literary agent. You submit your query and she goes through and offers comments. I would assume it takes a long time to get your query critiqued because this is a popular site. But you can learn a lot by going through the old ones as she’s been doing this for years. There are a lot of rules to follow and you are supposed to read through all her old posts before submitting. I won’t bother submitting to this one, I’m sure it would be a long wait.
Query Tracker is a site that has a lot of stuff on agents and publishers and more. They have a forum where you can submit your query. I haven’t looked into this one yet, but it appears that anyone can post feedback.
I’m sure there are a lot more out there, but these are some of the better ones I’ve found. You probably need a tough skin because you may not like what you hear. But the way I see it, any comments are helpful.