Loyalty discount help!

[Allthingsbeautyx]

id like to offer a discount for the following; Facebook check ins, nail pics, recommend a friend and some kind of loyalty cards. Obviously I wouldn't give discount for all the above to one individual, but what works best for you and your clients? I want to get my clients to spread the word and give them a little thankyou for their custom but without cutting myself short and giving everything away!

 

[Zabulec]

We give 20%off a facial and a moisturiser if the recommend a friend but they have to buy both, so we ensure higher receipt value to receive discount. Works well and word of mouth is most popular client origin.
Maybe discount something other than nails for nail pics? A way to get clients trying other treatments?
Facebook check ins might be costly if they get a discount every time...maybe one discount for fb reviews only?