Think about it from their point of view. So to start with,
1, free bloggers need content. If you want to get your item blogged about you need to create the content yourself and make it easy for the bloggers to blog about your product - nothing less than spoon feeding them and giving them all the credit. Make it easy for them and if you are lucky someone will blog about it. But the reach of that blogger is probably limited and little or no return will come.
2, you will need to incentivize the good bloggers by offering something. Not necessarily money or product. Google terms of use and the FCC are making it harder for bloggers to receive any kind of gifts without disclosures that turn many bloggers off. Here is the good news; bloggers probably don't even want the product anyway. As far as motivation Next to in line, after inbound links and $, is followers. If you have 1,000 Facebook friends, they will be interested in talking to you. Think of it from their side, what is in it for them. Show them that you will be able to move the needle on their subscribers and they will talk to you. Do you have an email list? There are ways to leverage that without bugging your friends. Tell the blogger that you will do one-three email blast selling their blog to your friends.
I hope this helped!
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