Perhaps I have stated the obvious but really, if you cannot decide
what the purpose of your blog is then you will struggle to write
meaningful, focused content.

I have been writing an article-a-day about small business issues
since 1998. In the beginning I was writing to attract visitors to my
‘portal’, which required I write about a broad range of topics and
therein was the trap - trying to be everything to everyone. It was time
to get more specific. (my emphasis)