If you want to do guest posting then make sure that your content is fresh and you are not at all a spammer. Then your post would be approved by the author.
I think the Guest posting is an effective way of promoting blogs written by you. The huge benefit with guest blogging is user readability. Your one blog posted as guest blog will be circulated among different other blogs.
Guest posting is good way to increase quality backlinks but make sure to change your author bio and keywords
A guest post is a relevant article placed on a website or blog by other person than owner. By guest posting you can get an editorial link, which is one of the best links to help you in pulling your website rank higher. To guest post you need to go through a long process. You need to find relevant websites for your niche ad filter them on criteria like total traffic, page rank, editorial guidelines, update frequency, lack of paid posts, Twitter followers, RSS subscribers, Technorati rank, and many other important criteria. Then you need to make contact with website owner to convince him about your content. Then you need to write the article, submit it and do the follow ups.