As of today, most of the link building efforts are geared towards enhancing the Google Page Rank to further improve the search engine rankings. This may not be a wise approach considering the rapid changes in the world of search engines.
While acquiring links, it might be a good idea to consider the following:
* Traffic on the website that you wish to get a link from (both quality and quantity).
* How many links are already placed on the page?
* What is the relative position of your link?
* What is the quality of the neighboring links?
* Is the page a content oriented or a link laden page?
If due attention is paid to all/most of the above, not only the links acquired would result in PR enhancement but would also further help generate quality traffic to the website.
As a rule of thumb, if a link is acquired with a mindset of generating traffic rather than increasing the in-bound link number, it is bound to help your website on all facets!