When I first was looking for paid post and such I looked around the internet. Saw lots of sites that offer such things and signed up at a few. SocialSpark has been one of my favorites though.
How does it work? You first sign up and fill out a profile for yourself/blog. You can set your own prices or go off the prices that they recommend for you. Than wait for offers to show up in your dashboard. Once you recieve a offer you can read what the company wants you to do for the post. Length, Links, Article, Etc… and you will see how many “points” they will offer for the post. Every 500 points is equal to $5. You don’t need to take every offer that comes your way so, pick the ones you think would suit your blog the best. They pay you by sending a paypal payment. If you have more than 1 blog you can add it also.