I've been setting up a lot of new sites lately. They consist of five pages of original, relevant content on a brand-new template (unique CSS) with relevant links on every page.
My problem is that these new sites bounce high on the Google SERPS for the first month or two for multiple keywords, and then they drop out of the top 100 altogether.
When I first create these websites, I add them to the link directories on hundreds of blogs and websites on different IP's and owners. This gives each site a good initial ranking boost on Google.
I'm guessing that Google crawls the initial pages and links, and decides that the site is a good one so they boost its ranking. However, after no activity (no new backlinks or new pages) for a few months, Google decides it wasn't really that popular after all.
So here's my question: If I could only do one of these things, which one would increase my Google ranking the most effectively:
1. Add new relevant backlinks pointing to the site on a regular basis.
2. Add pages of unique, relevant content to the website itself.
Thanks for any input!