Hi Rushdie,
It depends on what you're aiming for really.
Some people post every day as they believe this is better for seo. In many ways it is as google does have a preference to sites that update content regularly and if search engines begin to notice that you post every day they will begin to crawl you every day.
If it's merely rankings you're after - you want to be crawled regularly and drive lots of long tail traffic to adwords/banner ads etc - this is your best bet.
If you are trying to build a regular reader base then your focus should be on the quality of the writing then I would say post less frequently but write better quality posts. As long as you update your content on a reasonably regular basis you will still get crawled regularly and probably will still do quite well in Google.
800 words is quite long for a blog post, 400-500 is good and would mean you updating 3 times per week.