To keep your fans once you've been 'liked' and generate more 'likes' through their social interactions, you have to stay relevant. How?
It's certainly not done by blasting your fans with posts about your products, services, benefits and specials.
It's not done by posting every hour, flooding their notifications channels.
It is done by creating informative and entertaining posts that your fans can engage with.
It is done by projecting a genuine personality that makes your fans want to know more about you.
It is done by interacting regularly so your fans know you're really there.
But there's no formula for creating Facebook posts that will get you 'liked' and get your fans interacting with you. Good Facebook marketing takes a lot of work: to understand your target audience, to develop a strategy to reach and engage them, and to maintain engagement and growth that accomplishes a specified goal.