There are a few books that you shall know from cover to cover to claim that you know the basics of online... Inbound Marketing by Brian Halligan and Dharmesh Shaw is one of these books. If you have not read it, read it. It guides you in the basics of how you shall act to start pulling your customers in. We are increasingly turning to Google, Baidu, communities and blogs to find answers and to verify.
The book guides you to be found via search, blogs and offsite communities. It describes how you can improve your rankings in Google, get more traffic and how to build and promote a blog for your business, grow and nurture offsite communities (i.e. Facebook, LinkedIn, Twitter) and to measure what matters and do more of what works online.