A quick review: One of the main ways Google scores your site is on how many links are pointing to you.
Of all types of links, the best are one-way links that point at you, that are from sites with the same subject matter as yours (e.g. webcomics) and which are within a block of text.
One of the few types of site eager to deliver those precious links are webcomic blogs, which frequently insert links within reviews, interviews, news and commentary. Mini-blogs that accompany the current page of a comic are also valid, though less approachable.
A webcomicker with serious aspirations should have a site that appears at the top of Google search results when someone enters your comic name and words like comic or webcomic. Even better is if the comic name alone produces the comic as top result. An indexed report -- where the comic is accompanied in the search results by a little index showing the major headings within the site -- is best of all, and usually comes after a comic has established itself.
You want readers and journalists who don't have you bookmarked to be able to find you easily, and this is the best way. My analysis, still ongoing, suggests that as many as 10% of returning readers rely on Google to find their way back to you. Some don't bookmark. Others may be using a different computer or hand held device. Some may need to re-establish bookmarks that were deleted.
It's hard to find webcomics blogs using search, because a lot of dead blogs turn up, and a lot of Marvel/DC blogs are in the results. Happily, you can always find an up-to-date list of such blogs in the lower right column of this page. There is a more detailed version here.
Getting your webcomic on a blog is a matter of understanding each blog's needs. Study each one before submitting to see whether they want news, reviews, interviews, gossip, story tips or announcements. Then, provide what you have, as you have it. Don't worry about formal press releases. Most of us are quite happy with a just-the-facts, courteous email or inquiry.
I can't speak for anyone but myself, therefore I can't promise you will receive coverage or even get an answer. (I am a big believer in answering all email, on the grounds that not to do so seems insulting. We're all busy, and there are automatic response tools that can be used.)
Going back to the small blogs that increasingly accompany comics, trading brief write-ups with another comicker you admire will do much more for your site's prominence than trading links. Remember what I said earlier: links in text blocks are rated higher.
So there is a good argument for making blogs part of your routine. I didn't even have to mention the publicity and new readers you might receive.