You should decide early into your pro blogging what style standards your site will adhear to. It looks sloppy to switch styles between posts. If your site has multiple authors, a written style guide is a must-have.
- Do you use the first, second or third person when talking about your site?
- Are media sources italicized? (e.g. MobileTracker)
- How to credit sites
- How to link to sites (e.g. inline or at the end of the post)
- Image sizes and alignments
- How quotations are denoted
- How updates are denoted
By developing a series of standards, your site will appear much more professional without any extra work. After your standards are set, go ahead and slowly work on updating your archives… Visitors from search engines likely still visit older content and will benefit from the consistency.