I'd clean up any errors that google webmaster tools says you have,
Fix all 404 and other pages
Check on keyword usage through out your site, make sure you link to others a few times on each page but only sites you trust that are relevant to your site.
Write helpful content about your site's subject matter that will help users so they trust you further to use your service after they see the help works.
Monitor your traffic and see where users are clicking once they hit your site, and adjust the user experience based on that info and bounce rates.
See what your competitors are ranking and for what keywords, see about finding other keywords they may have missed, or just check to see how you could better use them on your own site.
It's no longer about being better and having more links from others. It's about how legit your information and content is to what your overall site is selling. If you have a carpet cleaning site but you give reviews and info about nothing once so ever, you haven't introduced anything to the SERPs and therefor will be left behind.
Content is key but helping your fellow users is the overall goal.
I'm sure others will mention the many things I failed to think of at this very moment to assist you