One thing I can't stress enough about a series: Every story must be able to stand on its own. You cannot rightly expect readers to read every story in the series. Come up with thematic and intelligible reasons for breaking the story into pieces.
Den1983 said:
However, if you do in fact do a series, find some way to complement it online. Whether photo galleries, a podcast breaking down each respective story of the series, whatever. Leave no stone unturned.
You should try to do that either way. And I can't emphasize this enough: Make it easy to find every part of the package or series from every other part of the package or series on your website. Clearly explained links are a must. Label things as "Part 4 of 5" in the headline. It's not a bad idea at all to have an editor's note saying, "This is Part 4 of a five-part series on _____________. Previously: Part 1 (with links), Part 2, Part 3. Coming tomorrow: Part 5.