Link Building Blog expounds a good way of increasing ranking. It suggests that getting links from trusted sites like .edu and .gov sites will help in useful link building.
The first step is obviously to search for links
Although there an tons of educational and government sites, a lot don't link out. The key to getting these links is to find sites that link to your competitors because they will probably be willing to link to you. You can do this by using Yahoo.
After locating the links it is crucial to get them:
Once you create a list of .edu and .gov sites that you want links from, the next step would be to email them.
My name is ____ and I am the webmaster of XYZ.com. I notice that your site links to websites that provide information on web design. XYZ.com is also a great resource that is about web design and your readers may find it to be very useful, if it was on your list. I appreciate your consideration.
A short and simple email will ensure such sites that you are not a spammer. So forward this mail to as many trusted sites as possible. But don't mail them constantly then you might appear as a potential spammer to them.