You mean in a natural way? Well the first thing is to invite your friends to like and support your page, maybe asking them to share your page on their timeline will help to (but don't force them). Then, make sure to update if necessary. Most importantly, engage; reply to queries though comments or personal messages. Share eyecatching images or good share contents where you can also attract engagements. But if you think you have to money to pay for the ads then I suggest you invest on it, that's the fastest way.
