http://blog.nowherejezfoltodf4jiyl6r56jnzintap5vyjlia7fkirfsnfizflqd.onion/opsec/torvsvpns/index.html
However when you do that, the VPN provider becomes your ISP, The VPN provider becomes the one who is able to spy on your internet traffic, instead of your ISP. By connecting to a VPN you are moving your trust from your ISP to the VPN provider, but since both your ISP and your VPN provider are centralised entities, you can be damn sure they are spying on what you're doing.