Offering service contracts can be used as one of your customer retention strategies. If possible consider setting up a maintenance program on a number of services that your customers can get at no additional charge in exchange for a small membership or signup fee.
Every time you get a new customer, offer a discount amount equal to the amount of the service contract if a service contract is entered on the spot.
With such service contracts in place, your customers are likely to call you first. The routine maintenance inspection keeps you and your customers connected which can bring you additional businesses when other services are required or desired.