For a writer your own blog is a must have in this day and age. If you write fiction (and I do) then this is not as important before you are published as it is after you are published. But if you are like me, then you enjoy getting a headstart on the competition. Plus, blogging is fun, great writing exercise, and something to do when your stuck at any point in your manuscript. If you write non-fiction, then a blog is crucial. Most agents do not want to even sign you unless you have an already established platform and a blog with a large following is key to that.
A word of warning though, don't let blogging consume you to the point of ignoring your WIP for too long.
My blog is very new so I am still researching what makes a great blog and finding my way around. I am sure you can tell from the random posts about various different subjects. I have no central theme.....I knew coming into this that I would be all over the place, hence the name. I also like the word 'hence'.
I have researched extensively regarding layouts, optimal placements, attracting an audience, and so on. Some advice I have taken seriously and some I ignored. I do intend to be more organized in the future. Having a format will help with that. Such as during the week being careful to only post on subjects that pertain to the business of writing and keeping the weekend posts for stories about my family or random subjects that interest me.
In my search for creating a killer blog, I found this post.
This guy lays it out for you, step by step.