While basic writing talent is innate , many of the skills for writing compelling blog posts and comments can be learned.
The keys: keep your copy lively, factual, tight, clear, short and most importantly search engine optimised!!!!!
Here are the main points to write a good blog and make sure it will be read:


1/ Short, declarative sentences are good. Web readers demand them.
2/ Link like crazy!!One thing that distinguishes blog posts from dead-tree journalism is that bloggers link prodigiously. Link to any other blog or website you mention!! and as noticed Kiia,there is now some blogs directories where you can publish the link of your blog!!
3/Aim at keeping your posts at about 250 words including good keywords!
4/Use subheads every few paragraphs, even in a 300 word post.
5/Use bold text and italics for emphasis on words and phrases and again LINK!
6/Make sure your posts are easy to scan.
7/Choose your voice and keep it consistent.
8/Don't be afraid to voice opinions.


Questions to ask yourself before you hit "Publish":
__ Is the topic clear to someone who only reads the headline?
__Does the lead paragraph tell who and what the story is about and why the reader should care about it?
__ Is the angle you've used likely to seem newsworthy?
__Would someone who knows absolutely nothing about this topic understand this post?
__ Is the post free of jargon?
__ Is it written in journalistic style and does it make an effort to be objective?
__ Have you peppered the headline and the post with keywords and phrases that will be attractive to search engines?


More information on : http://www.whatsnextblog.com (really good website about Online PR News!!)

I would just also like to add

- Choose your subject of expertise and stick to it
- Post regularly, daily ideally. This is preferred by readers and search engines
- Always try to be interesting, rather than regurgitating news from other sites.
- Encourage a community feel

For example, I love my celebrity gossip sites. There are dozens of them covering the same news, with the same pics. Why do I visit some and not others? The best ones are witty and updated daily, and also the comments posted are wittier than average....