My company's old site had very few backlinks (less than 20), but a couple were PR 6. We had less than 30 internal pages. Our content was updated once a month or so. What helped us most, besides PR6 backlinks, was clean, valid, highly accessible code. Within 1 year we had a PR of 6 on all pages. I am sure it can be done faster but this was my experience.
What does this mean?
Valid/clean HTML and a few relevant backlinks from pages with decent pagerank will help tons. You may also consider limiting your outbound links until you build up some pagerank of your own.
Submitting a sitemap to Google wouldn't hurt either.