First, I'd forget about doing guest blogging for the sole purpose of gaining links. Matt Cutts, Google's head of web spam, told us in clear terms that online marketers should stop doing this. (I'd add that people should not have been doing this in the first place.)
Rather, I'd focus on contributing to online publications for the purpose of increasing awareness and coverage of your company, website, product, and/or service among a specific, targeted audience. Don't worry about the links. They'll come naturally themselves as long as you do online PR in the right way.
For more, I'd suggest looking at my Moz post on the topic: http://moz.com/blog/an-introduction-to-pr-strategy-for-seos
In short, I'd focus on the websites from whom you would want links even if Google did not exist. If you sell widgets, then you want a mention -- with or without a link! -- on a website that is read by people who are interested in widgets. Think about this issue like this and don't worry too much about getting links directly.