There's little point unless you have the passion and dedication to be one of the best. If all you can do is repeat and rehash the work of others then you are wasting your time. People start and abandon SEO blogs on a daily basis. If you aren't 100% committed then take a look around and see if there is some other topic that you would excel at. A smaller niche done well will earn you more than you could ever do as a wannabe
If you start a seo blog or willing to start seo blog then you should plan how you will rank your website.Without seo knowledge you will never get to much visitor to your blog.If you have skill on seo then its very nice and technical and readable blog may increase your website visitor. Thanks
My best advice, as a SEO/Marketing blog owner myself, is to offer your own experience and views in addition to more general niche topics/knowledge. For example, you can write a case study every 1-2 months, or write about your SEO experiments. Then at the end of the year you can collect all thoe experiments and case studies in an ebook your visitors can download for free on your blog.
Instead of an SEO Blog can I suggest maybe a Personal Brand who specializes in SEO and blogs about your findings? There are way too many powerful competitors in the SEO Blog space and will probably be way to hard for you to compete.