Here are some tips on what I've seen work well.
- Find bloggers that you feel you and your brand / music are compatible with. Just a hand full, don't go overboard, otherwise you'll end up just spamming.
- Start a relationship and become friends with the blogger. Reply to their blog posts. Start a dialog through email. (Just with any relationship, this will take time)
- After you have established a relationship, which will require a few interactions, you can then start working closer with the blogger.
- If you have a show, offer to put the blogger on the guest list.
- Offer to write a blog post for the blog that is not about you but about something relevant to the blog's core topics.
- Send the blogger some of your music with out expecting anything.
- Rinse, Repeat.
Good luck.