Moving to Shanghai, China as an 18 year old...?

At your age it will be hard. No Education? What can you do? How are you going to just drop in to China and start something? You need a big plan. BIG PLAN! There are FEW if ANY JOB opportunities for you with what you convey in your question. Safe? Sure. China is not that dangerous of a place. Especially for Westerners. If you want to WORK legitimately in China you will have to have a work Visa. Do you even have a PASSPORT yet? Do you have a CHINA VISA to travel? To get a Chinese WORK visa you will have to be hired by someone in CHINA. They will get you a Visa. But who is going to hire you sight unseen and for what are they going to hire you for? Your only option is to teach English. Teaching English is a good job and it pays well. Sad to say Almost anyone can do it. Providing you are a native English speaker. Go to a TEFL class and get your degree in English Teaching. There are on-line classes you can take. http://www.teflonline.com/?gclid=CLOkuYC8yKICFYQvpAodlUWn_Q Get contacts through your class and find a company to hire you. Go to china that way. Now you are in China and you can try to do what you want.

Generally speaking you need a university degree to work in China. Anyone can do business, but working is mostly reserved for professionals. You could study and work part-time on a student visa, mostly it would be work teaching English. If you like little kids there are a lot of places desperate for teachers. However, if you want a full time job, you would not qualify for a visa. Perhaps choose somewhere in Europe. Many young British people take the opportunity to do some work on the continent. Another option is to go to a country like Canada or Australia where there are work visa programmes for young people. In Australia a 1 year working holiday visa will let you work for 6 months out of the year (or for the full year part-time).

China is a communist country, you don't vote and you will not have the same rights you used to.

If you want to work, you'll need a work visa. To obtain one, you'll probably need at least a bachelor degree. Good luck obtaining a visa without going to university.

An 18-year-old with no college degree and no professional work experience is unqualified for an employment visa in China. You may enter China on a 30 day tourist visa, but then you'll have to leave. You cannot work legally in China without being sponsored for an employment visa by a Chinese company or organization. I suggest that you get a university degree and a few years of work experience before thinking about China. There is a huge demand in China for foreign professionals, like lawyers and accountants, but zero demand for uneducated, unskilled foreigners.

Sorry but there won't be many choices for you in starting a career in China at your age and with your lack of qualifications, especially when you cannot speak Chinese.