The correct approach to link building is to first of all develop a good product. If internet searchers have done any searching at all, they know a good website when they see one. If your website does not appear professional and worth looking at nothing will happen from your visitors other than a bounce off.
They will not even stick around long enough to see what you have to offer on your site. When reviewing your site traffic, how many times have you seen that someone only stayed for zero seconds?
The other thing about having a good site is that the owners of other websites will be willing to link to your site. If your site feels right, they will naturally want to link to you.
This is perhaps the best method to get links. It is quite exciting when you get an e-mail requesting a link to your site. You did not even need to work for it. Another method of link building is to ask for the link. I have seen this done on some sites but not very many. Place a request in your website for a link.
Have some statement to the effect that if they like your site enough and feel you have good information, it would be great if they were willing to place your link on their website so other people can find you. This may seem a little bold, but it certainly will not hurt. Remember, if you do not ask, the answer is no.