We should strongly believe that for grab each and every link which gives us Do Follow link rel. I am always go ahead with Do Follow back links which pass link juice.

Article submission will really good for increasing fast back links. You can sure increase your site back links through this technique.

As per my seo experience, Link farm is called as Black Hat seo techniques. I strongly avoid this type of techniques. It gives us fast effect but I always love to use only White hat techniques.