I still am a 'new blogger', so I'm not very well equipped to give advice, but here is one thought that I have had that I actually haven't come across on any other 'blog tips' list yet...

Consider your intended readership.

When you are posting, always consider the people you are trying to reach.  Obviously we all have varied interests, etc., and talents, but it may not be the best idea to try to incorporate them all into one blog theme.   

My blog is primarily about parenting, and stay at home 'mommyhood', so the fact that I teach piano as well and work odd jobs as I need to doesn't really get a lot of blog space.  MOST of my readers are probably not overly interested in 'ways to encourage practicing' in piano students. 

If your focus is on writing - write a lot, and write well.

If you are attracted to blogs with a lot of photos and want your blog to be the same, make sure to include a lot of photos (lots of people are pulled in by photos).

I'm guilty of jumping around a bit in the underlying content of my blog posts, but I try to stay consistent and consider the people who will be reading the post.

Those are my two cents!