When hiring power or pressure washing services, look for licensed, bonded, and insured companies to protect yourself from liability. Check for certifications and ask for references to verify their experience. It's important to get a detailed written estimate that includes all costs, such as labor, materials, and equipment. Confirm whether they will use your water supply or provide their own, and ensure they use appropriate cleaning methods for your home's surfaces. Lastly, read customer reviews to gauge their reputation and quality of work.