As far as appearance is concerned, as long as it is not particularly scary, just dress neatly.
As for salary, it depends entirely on personal ability. The guaranteed salary is not high, mostly between 800- 1200. If the company is good, there will be a meal supplement!
The main source of wages is the basic salary plus commission. If you have the ability, a month 1000 yuan is also ok! However, the normal salary will probably be around 2000 a month, and it will reach more than 3000 in a good season. I mean normal. Of course, if you have special abilities, that's another story.
All the above are what my friends did and told me (D-Phone) and what I learned from some mobile phone promotions. I hope I can help you.