I was recently having a discussion with fellow Internet marketer Andromeda Edison of Internet Image Management, on the subject of whether it is better to have a blog set up as a separate domain, or as a subdirectory within the domain of your main web site. Here’s what she has to say:
"This depends and each situation I evaluate it newly.
"Some basic rules that I use to decide:
"1) If the keywords we are trying to get listed for are high competition then put the blog on the same domain as any link you an get to a blog post will help the overall site
"2) If you are working on a less competitive keyword you might want to do it separate (but if the competition is likely to increase with the popularity of the product or subject, you still want it on the same site)
"3) If you are working on reputation management for a name or brand then it should be on a separate domain.
"4) If you are going to use the blog only for "other" keywords than the one on the main website it can be separate though sometimes any PR you have on the main website will hep the other keywords – so this one can be a toss up.
"5) If you are working on a separate O/L or branding campaign for an individual in the organization it can be separate.
"I usually discuss this with the client and work out the long-term and short-term goals to help decide."