It is not about you, it's about the blogger. Don't focus on yourself, talk about what's in it for the blogger.
Do not pretend to regularly read a blog that you don't. You're not fooling anyone.
Don't pretend to be friends with the bloggers friends if you aren't really friends with them. This may help you get your foot in the door, but it destroys the relationship when the blogger discovers that it isn't true.
On the flip side, use your network to break through the clutter. Friends trust friends.
Don't reference a search engine that led to the discovery of the blog. It's irrelevant to the pitch and extremely impersonal.
Don't give away the kitchen sink. Your goal is to inspire interest and conversation. Give enough information to inspire interest, nobody cares to read a long email (unless you are friends with them).
Don't leave off without sharing a url for more information, as well as a real name, phone number and personal email address (this email address should include the name of the person pitching).
Always invite further conversation. Your goal is not just to generate one post, it's to build an advocate and information sharing pipeline.
Consider the context of the pitch before sharing it. Don't pitch in Twitter if Twitter isn't the right environment for the messaging. Just because there is less pitching in a given platform than email, doesn't make it a better communications vehicle.
NEVER send a form letter or use a "seeder". Your goal is to connect, shouting won't get you anywhere.
Don't add to the clutter, break through it. Anything you can do to deliver a truly unique message, be it the vehicle (email, facebook, twitter, phone call, singing telegram), the content or the offer.