It’s very tempting to bury ideas in a lot of extra talk (or writing). If an idea is good, it’s not usually necessary to support it with lots of explanation of why it’s so great. The temptation for writers (particularly those paid by the word – or the 600 page novel) is to take a good idea, and bury it in prose.
Blogging, as a form of writing, needs to be pretty short and direct (of course, you can always find exceptions), and to hold people’s attention, you need to grab them early. I think a good rule is to state the core of your ‘story’ in the first paragraph, and if necessary to expand on it later. If the idea is good, then people will read that, and get the er…idea, which will determine whether they read more. The more interested reader might read further down into your expansion, the less might just abandon you part way, but neither reader will likely get there if you spend the first two paragraphs on preamble and introduction.
Journalists know this – a quick glance across any of the stories on http://news.bbc.co.uk will show you this technique at work. An attention grabbing headline, a first paragraph synopsis of the story, and then (often most importantly) the real detail below. Of course, in journalism, its that later expansion which is often the important part. Headlines are often deliberately sensationalized, and the real story is buried a bit deeper. However, it’s a good rule to follow for any sort of writing. Get your idea out there, cut away the fat, and you’ll be more likely to be read.