Search engines rank pages based on relevancy and authority. As a link buyer you have many ways you can influence both of these.
Relevancy
• Peform keyword research and ensure your primary keywords appear in your page title. Make sure your page copy also includes secondary keywords and important keyword modifiers to help ensure you have the ability to rank for a broad array of related keywords.
• When linking internally try to use your keywords as the anchor text of the links pointing to the most important pages.
• When buying links try to get the keyword you want to rank for in the anchor text.
Authority
• Create and give away valuable tools and featured content, even if they do not lead to direct sales. If a person links at any part of your site it generally helps the rest of your site rank better.
• Link to important pages more frequently than you link to unimportant pages. Link to your most important pages sitewide.
• When buying or building links where you have some control over where they link at, try to point them at the pages you want to rank.