One of the strategies of SEO is building a relevant network of external links to the target website(s). Now, how to do this without being spammy?
A genuine strategy is to optimise the site in question, submit it to the relevant engines, find related sites and cultivate links from them, build supplementary sites on different servers and link from them, engage in social networking stimulating interest and discussion, make use of all the different search channels (images, local business listing, video, news) and generate relevant and timely press releases as appropriate.
You can then embark on a paid strategy using the major search engine sponsored link programmes but this is best used in tandem with organic SEO as it disappears as quickly as it appears.
But the genuine strategy often seems like pissing in the wind unless you can get access to a strong existing link source. How to do this? Answers on a blogcard please…