Your best route (if doing it all yourself, without buying services) is having a number of cross-reinforcing methods going on, such as:
1) Have a number of related keywords (with low SEO comp, not just one) totalling 5, 10, even 15 or more per site. Create at least one page of unique content per keyword, and ensure each article is decently SEOed do that each page has some innate authority.
2) Each page of the site should link to each other in a kind of wheel (internal linkwheels will not be punished, as internal linking is construed as natural). The main page should have a "recent posts" or articles spot that links to each of the subpages (and each title should contain the keyword).
3) Create a corresponding web 2.0 property linking to each webpage on your site you seek to rank for. If you use blog comments for these links, you will have maximum control, and usually the ability to link twice from one backlink page. Apply two legs of quality backlinks both to each property, and to the site---on 'leg one' put at least 10-12 quality links to each Web 2.0, and to its corresponding site webpage. On 'leg two,' apply 10-12 links to each property, and to the main page, like so:
4) For a site with 10 keywords/10 pages of content, this two leg off-page linking structure will total 200 links not counting the properties, consisting of 20 backlinks per web 2.0, 10 of the same links per each sub page, and 100 links to the main page.
Here's where the cross reinforcement kicks in. For a low comp keyword, as little as 10 good direct links plus the on page SEO per subpage, should give each page good authority. The cross-linking will result in the authority of each page further building each other. The 100 links to the home page will make its links to the subpages rank them still higher. Likewise, the 20 quality links to each web 2.0 should be enough to rank the property to the top 50 or so for the keyword, which should help push the sub page containing it into the top 10, given the other link reinforcement.
