But before you can start doing these sponsored reviews, your blog must be accepted. For example, ReviewMe, one of the early pay-per-post pacesetters, require that a blog must have a minimum number of citations, traffic, and subscribers to RSS feeds.
That puts a damper on many fledgling blogs (including this one) whose time have not yet arrived for them to be included into this so-called "elite group" of reviewers.
ReviewMe look at your traffic ranking data from sites like Alexa, Technorati and Google PageRank using an algorithm that determines your blog's standing.
Where your blog stands in the ranking determines the fee advertisers will pay in order to have reviews on your site. There's a different set of fees (ranging from $30 to $1,000 per post) for each blog based on the calculation.
If you do qualify to become a reviewer, then you are required to disclose that what you're doing is a paid review. Now, you are expected to carry a "disclosure policy" or a badge to signify that your blog does paid or sponsored reviews.
You can write reviews in your blog's normal language (for example, English) but if your blog is Spanish or Japanese, then you should be writing in those languages.
What are the review guidelines? According to ReviewMe, they'd like bloggers to write in a way that makes sense for their unique niche and audience. All reviews are expected to be at least 200 words long and you'll have to disclose that they are sponsored.