As we know SEO in an ongoing process and you need to work daily for ranking and positioning keywords.regularly you have to do
Link building etc...
Link building is the best practice and you can create back link through many way's.
Like link exchange is very tough and very time consuming but it's good if you can do this and second all depends on you like article submission, directory submission , forum posting , social bookmarking and blog commenting are the main things that need to take care of on daily basic.
As so many guys provide, there are so many methods of link building daily.
But according to my own experience, these are more effective than others among these methods: