I'm just an amateur student (I took one year of Chinese in the US, and recently started a year-long language program in China), but I offer the following suggestions:

I think the first words a student of Chinese should learn is not 你好，but rather 怎么说________. Then the student can ask how to say "Hello" or whatever else the student wants to learn. In short, the first chapter should not be about introductions, but rather words and phrases used to learn a language, such as 怎么说？，意思是什么？，应该说什么？，可以说？，声调，名词，动词，etc. This way, the students can immediately start using Chinese to learn whatever other parts of the language they are interested in.

Taking this idea further, perhaps first introduce whatever is needed so that the class can start to function completely in Chinese as soon as possible. I know people want to learn practical everyday conversation, but if you aren't taking Chinese in a Chinese speaking country, the only practical environment you have is the classroom, so you might as well make the most of it.

I also wish my textbooks introduced all the crazy particles much earlier and all at once. Such as 呢，吧，了，啊，嘛，哎，哇，呀，嗯，哦，etc. Their sheer frequency and seemingly erratic usage constantly gnawed at my curiosity, and was the source of most of my initial frustration when I first started chatting online with native Chinese speakers.

Perhaps my teacher just sucked, but it was way too long before someone formally and clearly explained the rules regarding the tone changes to me. Such as when and why 不 changes from fourth tone to second tone, etc. How are you going to teach a student ni3 and hao3, and then in the next breath pronounce it as ni2hao3? A simple awareness of these rules would have saved me more than a few headaches during my listening comprehension sessions.

Finally, I don't know the proper protocol and regulations regarding the inclusion of outside resources, but if possible, I think a textbook should include suggestions regarding additional language tools. Some examples include: Heisig's Remembering the Hanzi, Anki, Yellowbridge, Pleco, Chinese IMEs, Perapera, QQ, and of course, Popup Chinese! Every time I randomly came across a new tool, I would always say to myself, "If only I knew about this when I first started!"

Hope you find something of value and good luck =)

Danny