The consensus, I think, is that queries are tough to write, but make all the difference in garnering a request.
In my opinion, the blurb is everything. Of course make the other parts of your query polite and professional, but what sells your story is not how many contests you've won, not how long you've been writing, the classes you've taken, the theme of your story, etc.
Eventually we sell ourselves. But for first glance, it's all about the story.
So how do you go about writing a great blurb? And what should be in it?
A Plot Catalyst: This is super important. Agent Kristen Nelson did an in-depth series on this. Your blurb should start with the plot catalyst and cover what happens in the first 30-50 pages. Then you end on a hook.
The Hook: What is the danger (emotional or physical) that your character is going to face? The major decision he or she has to make?
In the words of Miss Snark, a good query contains the following formula:
Who is the protaganist?
What dilemma does he face?
How does it get resolved?
Answer each question in less than 25 words. That's the skeleton for a good query letter. It may not be your finished version, but it will give you the bone structure you need.
Another helpful post quoting Miss Snark is HERE.
What do you think of all this? How strong is your blurb? Have you been able to boil your plot down to its bare essentials? Have you studied the backs of books lately? Any advice to add? (since I'm still learning and working on this, just like you)