DIY Blog Tour: Let er rip
You can't send them as a group email. Not only will they all want different information, but it's rude.
Your goal is to be personable, yet professional. This means addressing bloggers by name, not the name of their blog. And don't just send the form letter we wrote yesterday with their name filled in. Show bloggers that you've put in the leg work of scoping out their blog. You can do this by congratulating them on a recent achievement, mentioning a book you picked up based on their recommendation, or even just mentioning a recent post. You can lead into your book by referencing books similar to yours that they've reviewed in the past. The key is to show that you didn't just pull their name off some master list and shoot off an email.
And don't forget to be polite. This should go without saying, but always use please and thank you. You aren't offering them a golden goose, here. You're asking for a favor. A gracious attitude is always appreciated and never hurts.
Be sure you give yourself plenty of time to send these out. I'd say, a day or two at the minimum since it can be tedious and you'll probably want to break it up. Just be sure to keep excellent records so you don't send two requests to the same blogger.