If you have (or can cobble together) a syllabus and you know what you're going to be teaching, presenting it in some digestible format is good. Failing that, some idea of how lessons will go in general and what you as teacher will focus on. Some idea of how you intend to assess work.
Introducing yourself is always necessary, of course. At least your name and where you come from. But since you'll be using the target language to do your introduction, you might as well turn what you say into some kind of lesson. For instance, what language function will you be using as you speak - telling stories, using past tense, Q&A? As you do the introduction, will you use and emphasize certain elements that students can then go on replicate in some activity? Etc.
The absence of a projector can be a good thing. Simple diagrams on a blackboard are, I have found, sometimes much more engaging than a ppt. You have to draw them on the spot. They engage imagination. They don't get as often photographed as ppt screens do...
China protip: something I wish I'd known my first year - a passing score in China is "60", not "50". My first semester in China I inadvertently failed about 12 students (and boy, were they were annoyed).