First of all, Google needs a reason to rank your site before others.
If you have a website with a few pages and haven't updated anything on it for 2 years then Google will rank the guy who updates his content regularly before you. Google makes it's money on advertising and as such needs to ensure that only relevant web sites are presented to their users, otherwise it's users would move to another search engine provider to get a better match for their searches. One of the most important elements for search engines ranking your site is your site's Domain Authority which is determined by over 40 other metrics, one of which is the number of other sites linking to yours and their Domain Authority.
Social media links from sites like Facebook are very important in letting search engines know that your site can be trusted and people are engaging with it. This is where blogging can help, by creating useful blogs relevant to the content on your site that help solve other peoples problems, you increase your chances of social media users sharing links to your site and thus increasing your important Domain Authority.
So what type of blog will increase search ranking
The main point is to offer solutions to the problems that your target audience is searching for. If your are solving your target audience problems then they are much more likely to share a link to your site with friends on social media. Also other domain administrators or site owners will also be more likely to link to your site on their personal blogs, increasing your Domain Authority and your search engine ranking. Some points to keep in mind when writing your blog are:
- Know who your target audience is
- Choose a title that will appeal to and find your audience
- Identify groups within you audience that might have specific needs and write blog post specifically for these (for example a car dealership might write a blog on assesability options for disabled people)
- Choose topics by making a list based on popular questions posted on relevant forums
- Make good comments on other related blogs and leave a backlink (see blogtyrant.com for some good tips)
- Make your content relevant to your target audience
- Solve problems that you think your target audience are searching for
- Update regularly