Update - Astrill is no longer offering a free trial or a money back guarantee for customers in China even if you sign up with another VPN. Read this blog post for more information. If you are outside of China then you should still be able to get the free trial.
If you are in China and you want to try a VPN risk-free ExpressVPN is my top recommendation.
ExpressVPN offers a 30 day money back guarantee with all accounts.Try it out for 30 days with no risk. They can offer this unbelievably long MBG because so few people ever take advantage of it. They know that their VPN works better than anything else so they are confident enough to offer 30 days.
Get an additional 3 months free + 30 day money back guarantee
For more VPN options in China (all with free trials or money back guarantee periods) check the Best VPN for China page.
Astrill is the only VPN provider I know of that will give you a free trial without giving them your payment or credit card information. There is a catch if you are in China. This 7 day free trial will only be available if you go to the Astrill website using an existing VPN or proxy. If you connect from overseas or connect from China using another VPN then you will see the options below.
However, if you connect with a Chinese IP address then you will see the options below with the free option gone.
If you are in China without a VPN and you don't need the free trial then you can get to the Astrill website using this link. If you want the free trial then it's recommended to sign up using this link before coming to China or finding someone in China who has a VPN that you can use to sign up using this link. If you can't find anyone with a VPN to help you then look for a foreign bar or restaurant that has a VPN router for customer use.
Note - You need to verify your mobile phone number by SMS when signing up with Astrill whether it's for the free trial or a paid plan. If you don't feel comfortable with this then don't sign up with Astrill.