Dofolloew directory submission is best way for link building . if you have more trick for it please post here..
Directory is just one of the simple to get backlink, not the best way. There are many other simple way to get backlink such as forum posting, blog commenting, social bookmarking, article submission etc
having a good content is a sureway to get a backlink too! sometimes i get discouraged in submitting to some directories because of their reciprocal requirements.
No one link building will rank you higher now. You need a diversified linking strategy now to rank high on Google and appear as authority. However yes, any do-follow link helps.