Redirecting Customers from Facebook or Twitter to My Site

I apologize if this is not the right place to ask this question (close if necessary)

I have my Facebook page for my website which I am doing my advertising for. I want to have different coupons for different campaigns (say, a Christmas campaign) and redirect them to my site.

My question: Is it good to redirect users to a custom landing page on my site eg: http://mysite.com/facebookad and show different content or should I just do http://mysite.com/?ref=facebookad and keep the same content up?

I'm new to marketing so I'm not sure who to ask.