1. To begin traveling; to start a journey. We were just about to start off when I realized that I had forgotten my passport. Let's start off soon—I'd like to get to the campsite before sundown.

2. To do some particular task or action as a means of beginning some process. A noun or pronoun can be used between "start" and "off." Lets' start the meeting off by going around and introducing ourselves. I don't think you should start off the presentation with an anecdote like that.

3. To instruct, cause, or compel someone to begin on something or to begin doing something as an initial starting point. A noun or pronoun is used between "start" and "off." We'll start you off with some easy tasks so you get the hang of the job before we throw you into the deep end. They started me off washing dishes, but said they would train me to be a cook once I'd been there for a couple months.