I don't bother,I have a data base,but a lot of my work up until a few years back was eot cleans,so always changing tenants, all they were wanting was cheapest price,however what I did do is had a load of business card size stickers made up,with all my details on,with a space for a date,saying these carpets were professionally cleaned on and to keep them looking at their best call me in 12 months time,have found they work,just got back from one today,3rd time I have cleaned that place for different people,so a total of over £700 as it was a big one.