Talk to your clients. The first step is to find out exactly what your clients or their parents, if you are tutoring minors, expect from you as a tutor. You might find out that you both have very different expectations. Adjust your instruction accordingly.
Set a few short-term goals for your clients. Your long-term goal may be to help your clients pass a class, but the ability to see regular process is uplifting and encourages confidence on the part of both students and tutor. Reassess your goals on a regular basis, depending on the progress of your clients.
Monitor your feedback. Make sure that you ask leading questions without giving away any answers, and that you also give your clients positive reinforcement. Identify problems without correcting the answer for your students.
Listen to your clients. Often, you can catch errors simply from a student's verbal explanation of a problem. Ask your client to describe how he arrived at that answer, and you may be able to identify the problem area.
Polish the little things --- arrive on time, or even a bit early, and project a friendly, confident personality. Make sure that you organize your teaching materials; keep clear records and logs.