What is a blog?
A blog is a website in which items are posted on a regular basis and displayed in reverse chronological order. The term blog is a shortened form of weblog or web log.
Authoring a blog, maintaining a blog or adding an article to an existing blog is called “blogging”. Individual articles on a blog are called “blog posts,” “posts” or “entries”.
A person who posts these entries is called a “blogger”. A blog comprises text, hypertext, images, and links (to other web pages and to video, audio and other files).
Blogs use a conversational style of documentation. Often blogs focus on a particular “area of interest”, such as Washington, D.C.’s political goings-on. Some blogs discuss personal experiences.
http://en.wikipedia.org/wiki/Blog

Effective Blog Tips
The user experience of a blog is determined by two factors – author activity and reader activity. Ultimately the goal of a blog is to increase the activity and create discussions; provoke thought – create a knowledge base.
The below points highlight areas that can be focused upon in order to achieve a successful blog. .

Accessibility
Give the readers an ability to receive posts via email – you cannot assume that users understand RSS feeds.

Controversy!
Most successful blogs create conversations on the web about topics that have yet to be discussed in detail; topics where people have definitive opinions. Think about intense discussions in a physical sense – and relate it to an online environment. Same principal. Topics that are controversial are great for blogs as they start conversation.
Why would someone want to get involved in an outdated topic that has been solved, proven, or talked about from all angles?

Voice
You as a blogger are an author. People read specific books because of writing style, opinion, (subject) and personality – the same principle applies to a blog. Test out your writing styles to match your readers.
Which one works best? The one where you get replies!

Become a Subject Matter Expert (SME)
Do not be scared to discuss on other blogs in the same topic. Others will see your posts, and consequently want to know your back ground and see how much you really do know!
If someone goes to a blog with zero comments for every post, sometimes that can give the impression that no-one reads it.

Link Link Link
A smart idea would be to link various viewpoints – which will keep readers coming back for more conversation. This will also help in getting people linking back to you.

Writing Style
Look at the direction of the way your posts are written. Do you want to end your blog post with an open question? Or a closed question?
Having a closed question really ends any conversation. Think about this. If you were talking to someone and said:
“Would you be interested in going to Hawaii?”
Reply: “Yes”
OR
“Why would you want to go to Hawaii?”
Reply 1: “Because of the nice beaches, the surf, the people, the history of Pearl harbour”
Reply 2 “Why is Pearl Harbour so talked about still?”
Reply 3 “Pear Harbour is part of the world history….etc”
This conversation could go on because it is emotion based and gets people thinking and wanting to voice an opinion. Rather than blogging about would I yes/no be interested in going to Hawaii.

Another way is to research and learn from other SUCCESSFUL bloggers.