The best visas for long term stay are either a student visa or working visa. To apply for a working visa you will have to find a job at a company that is authorised to employ foreigners. You’ll then have to return to your home country to apply for the visa. Student visas require less documentation. However you can’t legally work on them. Under the new rules I’m not if you are required to leave the country or return home to switch to a student visa. You should ask at a local uni. to find out more.
As a last resort you could get a business visa in HK. Check out Charlie’s Chengdu Living post on the subject.