If you know your client and their organization well, there’s a reasonable chance that you will inadvertently “help” participants with their answers. In order to get the best information possible, create questions that are objective. Avoid asking questions that are hard to understand or answer. While you are interviewing, don’t finish people’s sentences for them, or use body language or verbal language that is sympathetic. You want to take in their answers, and not have them tainted by your own insights. You can add your perceptions to your report afterward.