To engage a grease contractor, you can start by searching for companies that specialize in grease trap cleaning and maintenance in your area. You can also ask for recommendations from other businesses or check online reviews to find reputable contractors. Once you have a list of potential contractors, you should schedule consultations with them to discuss your specific needs and get quotes for their services. When evaluating contractors, be sure to ask about their experience, certifications, and insurance, and make sure they are licensed and insured. You should also ask for references from previous clients and check those references before making a final decision.