I used to use a £10 off your next clean, but it all got a bit tedious in the office!!
When you offer them cards tell them to put their name and address on it so you know where the referal came from, when you get the card back you then send a lovely letter saying how pleased you are for them taking time to refer you, and a £10 off gift voucher.
I found it was hard work to keep upto date, referers would want only 1 carpet cleaned and £10 off (which I was hoping they would have 2 cleaned on a visit) and then you get the ones that have refered you but didn't pass the card on so didn't get the reward so then you get animosity and a lost customer!
Scrapped it, too confusing for both parties.
Shaun