What should a professional blog have?

A blog must always have interesting content to be successful. I don’t know if you need to worry about anything else. Focus on what blogs are made for: content. If people are reading, you’re doing something right. And the other thing is: calling a blog “professional” is a bit inaccurate to me. Blogs are supposed to be informal, but I think I know what you meant. Good luck!

I mean’t – of course the biggest thing of a blog is to have interesting content. But blogs should still have other features in it, well all the other successful blogs do. sidebars, social sites, etc….

A target audience.

Aside from interesting, original material of one’s own (not plagiarized or violating anyone’s copyright); good spelling, punctuation, grammar and syntax; interesting, believable and honest reporting / writing (or fiction that is labeled as such); logical argument and honest examples for political, economic and other “cultural” reporting, and a place for opposing points of view.

That, and moderation, I suppose. (On the part of the blogger and the comments that are added to the blog from ‘outside’.)

What do you mean by “professional”? Do you mean a blog of a professional web designer, or just a blog that belongs to a certain professional, or do you mean just a blog that was designed by a professional?

Professional blog platform. TypePad.
http://www.typepad.com/

Also, the more linking the better.