Unique content is always your best bet. At the risk of giving a rather vague answer, the best way to get "likes" is to write content that people will like!
Think of a common question or problem that people have, and try to answer/solve it. Become a helpful resource, try not to just regurgitate advice that anyone can find in 5 seconds with a Google Search.
There isn't a lot of science behind it... you sort of have to work with trial and error. Learn your audience, learn what they like and what resonates with them. Over time you can refine it into a winning formula, but each niche has it's own group of people that need to buy in to make something successful.
For a humorous take on this advice, see the following: http://theoatmeal.com/comics/facebook_likes