Engaging on the techniques like blog commenting, forum posting, article and directory submissions, social bookmarking, classified ads, press release, link exchange and online groups helps you get lots and lots of back links. Just make sure to get back links on relevant and DoFollow sites because Google gives more value on these kinds of back links.
You need to go through DMOZ in order to get your link listed in the Google directory. I disagree with this and I think Google needs to cut out and ditch the middle man (DMOZ) so people can get past the corrupt and lazy editors as well as not having to wait 3 years to get in.