Link building is not something you should launch into without doing some planning. You need to think through the overall plan, because doing so will help you obtain significantly better results. The basic reason for this is that the best way to target your campaign is not always intuitive. There are some critical areas that you should think about before launching your campaign.
1. What is your current link profile?
You'll want to pull a backlink report on your site and make sure you get PageRank data on the page provide the link, and the home page of the site providing the link. If you are using SEOmoz' Linkscape, you can also make use of mozRank, Domain-Level mozRank, mozTrust, and Domain-level moz Trust.
If you already have 10,000 (or more) links, a strategy to obtain 100 more links of similar quality is not for you. You need to get 1,000 links or more, or get a smaller number of links that are of higher quality than the ones you already have.
2. How competitive is your market space?
If the competition has 30,000 links, and you have 7,000 of similar quality to theirs, doubling your link count may not be enough to move in front of them. Of course this interacts with the search terms you are pursuing, but you still need to have a sense of the competitive picture so you set your targets in an appropriate fashion.
3. What is the competition doing?
Try to figure out the link building strategy of your competitors. Are they focusing on blogs? News sites? Major link bait and social media sites? How are there various strategies working for them? You might want to emulate the ones that work well for them. You should also try some of those great ideas you have, which they have not thought of yet. Differentiation in link building strategies is good.
4. Where are the great links found?
Where are the opportunities for really high quality links in your space? Where are the opportunities to find large numbers of relevant links? This is one of the most critical components of the planning process.
5. What content have you deployed, and what content can you deploy?
People need a reason to link to you. You can compensate them, but that is against the Google webmaster guidelines. You can trade links, but using that as the major pillar of your link building strategy is also problematic with Google.
Ultimately, you need to publish great content (or tools) on your site. You also need to avoid publishing "me too" type content. Plan on publishing stuff that establishes your organization as a leader in its market. You are not going to get the great links in sufficient volume unless you have this piece well covered. Note that this will be where a substantial portion of the cost of obtaining links will end up going.
6. Are there branding considerations?
One of the classic examples of this is a very conservative business that does not want to promote content on Digg, because of what they would have to do to succeed is not in keeping with their brand. Have possible branding considerations in mind to filter out ideas that senior management of your organization will not be able to live with any way.
Pulling it Together
You then need to take all this data and consider it as a whole. Some ideas are almost a given. Contacting people who link to your competitors is an example of that. If someone links to your competitor, and you have equally good (or hopefully better) products, services or content, you should contact them and ask for a link. This type of campaign can work really well.
However, never let that be the only thing you do. You will never get 100 percent of the people who link to your competitor to link to you. In fact, getting 20 percent to link to you as a result of contacting them directly would be an amazing performance.
Make sure you include other types of campaigns that are suggested by the research you have done. Make sure you are getting the right quality and quantity of relevant links. Make sure you have the right content to back up your link building plan. And, of course, make sure you aren't messing up your brand in the process.