SEO is a delicate balance between on page optimization and off site popularity. One way of quickly increasing your Google ranking is to build effective links back to your pages, a long debated subject is the effectiveness of reciprocal links. Google's advice is to generate back links that are natural in creation, this is why there is a big question mark over reciprocal links.
A reciprocal link is when you link to another page and a mirror link points back to your page, however this is not the only type of reciprocal link. Many sites have a links page, this is used to build links pointing to various sites around the web in return for a link back to the home page, it is also know as a link farm and is punished significantly by the engines.
A very popular way of building links is to exchange links with popular directories . In my opinion this is an ineffective way of building links. Remember Google wants these links to be natural and listing your page with a directory in return for a link back is not a natural link to your site. It is artificial and Google is not going to award this link the same as it would a naturally acquired link.
If you're going to build reciprocal links then there is only one real way to accomplish this naturally. Firstly you need to publish quality content on your own site, once you have done this search for other articles, blog posts and forum threads around the web to potentially consider exchanging links with.
For a link to be natural it needs to be relevant and of the highest quality, think to yourself, if Google were to review this link manually would they see anything wrong with it? If you can honestly answer no to this then you are on the right tracks. Even though this is a natural way of building a reciprocal link Google is always going to give a one way link more weight, this is because it is almost guaranteed to have been awarded because of quality and usefulness.
Another aspect you need to worry about it is the depth of links. Reciprocal links are never going to look natural if they all point back to the home page of a site. Try to build your links to deep pages of your site, this will help your overall domain profile and increase rank on deeper pages.