You can buy some applications for Link building. Now a days,those apps are available ina very cheap price..
Perhaps you 'd like to try signing up to our free text-ad exchange machine. The good thing about it is that it uses keywords to target other sites, so you normally get high ctrs for your text ads. Also text ads are completely themeable so they 'll integrate seamlessly to your website. Take a look at ads.4everyplace.com for details...
He's got an excellent point. This is also what I'd suggest you do. Just takes some time to research it all.
Here is one. I am using this, it takes sometime but is a good automatic link exchange. http://www.webmasterlagoon.com/automate/login.php