Good textbooks adjusted to the age of a student are always a safe bet. There are lots of materials for starters on the internet. To answer your question, the traditional topic to start with, as I remember it, was in most cases My family.
It may do. There's a good chance that a beginner Chinese student won't know the alphabet, so that's one area that would need a lot more work than in other countries.
I'd be tempted to start with whatever happens to be in the room at the time. It will all be stuff that will come up again and again (book, pen, table, chair, pencil, etc) so it's as good a place as any to start. Combine that with a relevant grammar structure (It's a.../they are). Add to that some functional language that will be useful throughout the course (write, listen, speak, read, open your book, stand up, etc).
Other early topics would be colours (introducing adjectives) and family (introducing personal pronouns).
There's a good chance that a beginner Chinese student won't know the alphabet, so that's one area that would need a lot more work than in other countries.