Originally Posted by riko

If your site(s) is a long term project, use only, I mean ONLY, white hat techniques. It takes time and lots of work, but eventually it will pay off.
Don't do spammy stuff, don't use any kinds of software, don't hire a company that says it will place link to your site to 1000+ blogs and such. The last thing you want is that Google and other search engines hurt your site and it's an extremely long way to get back on track after being penalized (sometimes it is better to start all over again).
Build links slowly and steadily.