The system isn't that rigid. You can get a job no problem, though it'll be a temporary one. You can do tutoring, teach part time or find any job that'll need someone in your field, but it'll be part time.

Anything else would require you to sign a contract, will would put you in the legal obligation of having to go through an administrative roller coaster.

Be advised that there is no legal way for you to work as you do not have a work visa. You can get a job because most 'employers' won't care about your visa status and just pay you cash at the end of the day, but be warned that if caught by police while working, you might face to get deported and refused future visas.

A student visa will allow you to study, not to work for money, or for free.  It is a sure way to be into a heap of troubles if caught.  And they are starting to check into this issue more often than years ago.

What you could do, and some may consider it still not right, is to do your crochet and find a store that will be willing to sell it for you, but that could open another can of worms, they may claim some of your work was stolen and refuse to pay for it.

You are lagally aloowed to work 15 hours a week on your student visa. That is a new rule started in 2011. But becarefull if you go over that they will catch you.

maybe go and ask at the  Chinese embercy near you
from the horses mouth as opossed to the horses Ass that the trolls will offer

you will get somebody who speaks english and they will give you the info in writting (english)
please post the answer when you get it and good luck
 

when you arrive tell the immigration officer you want to work and you will not accept no for an answer

To make things crystal clear, here are the official rules:

Student Visa is divided into X Visa and F Visa.  X Visa is issued to aliens who come to China for study, advanced studies, or fieldwork for more than 6 months.  F Visa is issued to aliens who come to China with same purpose but for a period of less than 6 months.

The organization must be accredited for offering courses or internships to foreigners. They will send you a JW201 or JW202 form and an admission letter. Submit these with photocopies with your visa application.

You are not permitted to work on this visa 'without permission'. You should contact you university or employer after you have settled in to see what can be arranged. However, many students moonlight, especially teaching English. Should the authorities discover this, you will probably just have to stop though expulsion is always a small possibility.

X visa is only for 30 days from the date of arrival during which time you and your university or employer must seek a Temporary Residence Permit for the duration of your study or internship, to a maximum of 12 months.

Now, if this are the "official rules" and are so ambiguous and confusing (you can but if caught may face expulsion ), do you want to take a chance?.  Your life, not mine.

Very very carefully and  foolishly...

unless they want to learn mandarin, why else would they want to come to China and study ? 

OMG this question is well over a year old.

Yes you can work illegally.

you can teach private lessons which is the easiest way

work in restaurants is another

As indicated above, basically - legally - NO! (unless you're really lucky, as Expat John indicated above).

In case you missed that - LEGALLY, NO!

And, as a qualified and professional English teacher, please don't go teaching English - it only makes the wages do down for those who are legally working here! (not to mention, the quality of education)