Target highly searched keywords (takes more time)
Submit your attractive articles to social bookmarking sites (takes less time)
But I think I after Google penguin update value of keywords get decreased. But Still we need to target keywords somehow.
Penguin update have not decreased the value of keyword, rather I would say it has increased the value, the only difference in targeting keywords now is that you have to spread your website all around the web.
Spread your website in broad way on internet rather than going only deeper.