Anyone wanting to use ANY free proxy service or FREE VPNs should read these three articles/blog, study FIRST !
Now with that said, I believe one of the safest and beneficial VPNs would be (Disconnect.com) Not only is it private,but filters malware,and ads and more. They are similar to Adgaurd who came out about the same time. Both have free and paid versions but Disconnect is only $5 a month and located in San Francisco US. Adgaurd is located in Russia. I think these days,many people prefer to use regionally close providers for some sensitive things. The advice above to build your own tunnel is the best advice if you have the means. But free services these days come with strings attached. Do your homework folks.