When utilizing an aggressive linking campaign, don't start linking into multiple domain networks which are all hosted on the same server or buying a series of links hosted within a single IP addresses. What your website needs are natural links that will be gained over a period of time. One of the best ways to achieve this is to comment on do-follow blogs (not spamming, but commenting on a few per day) where your website link is naturally growing.
The pagerank quality of those sites you want to link to you must appear natural to the search engines. Be careful to not only link to sites with a high page rank of 8 or 9. You should also seek links from a good range of sites with both high and low page rank values. This is especially the case for new sites and submitting articles to the various article directories will achieve this.
SEO Tip #3
Try looking at your link campaign from a purely scientific view. Basically, you need to find out what the visitors to your site are searching for and then find out which phrases convert to sales and then target your link text towards these visitors. Once you have determined your highest value phrases, you then apply those phrases in the anchor text you request from your link partners. Using this method allows you to request links based on the highest Return Of Investment (ROI), as well as appearing natural to the search engine spiders.
By applying the strategies above, you will attain a linking campaign that is both relevant and highly targeted to your main search phrases. Link quality is far more important than link quantity and anchor text is more important than pagerank.