Ways to Promote Facebook Page

I need information and/or techniques on how to promote a Facebook page!

Through my research I have come across only two ways, either pay for advertising or commenting on other pages.

I am thinking about the commenting on other pages, using Facebook as my own page, is this a good technique?

Please also provide me with any other ways that you personally have discovered work well in promotion of a Facebook page.

Much Thanks,

BiologyWebmaster