When you write a request by email, you want to keep it concise and informational. In your first line, you should write something along the lines of, "I would like to request a review copy of [title] by [author] (ISBN: [ISBN], ISBN-13: [ISBN-13])." Make sure you double-check ALL of this data at the publisher's website, especially the ISBNs.
After that, you should include one or two sentences as to why you think that book would be a good fit for your blog. For example, maybe you love to read light-hearted contemporary and that's the kind of book your requesting, or maybe your blog is having an up-coming event focusing on dystopia that you want to feature the book in.
Next, have a sentence or two with information about your blog. Include the blog title, URL, how frequently it's updated, how many followers, and how many views. You should also add anywhere else you would put up the review - Amazon, Goodreads, Library Thing, etc.
|But also make sure not to inundate them with requests!|
Note that some email addresses are hard to find! I have a list of every email address with every major publishing company and imprint, so if you would like a copy, just shoot me an email.
Finally, the subject line should say something like "Review Copy Request: [insert book title]".
That's all! If you have any questions or any other tips to add, post them in the comments!