turn into opponent
I have been doing brazilin jiu-jitsu for two years now and prior to that Judo for one year. I am no expert, but one thing i do know is you never turn into the choke. You always want to turn towards the person. If you turn away and towards the crook of your opponents arm the choke will sink in. If once the choke is sunk in, get keep your chin down so the pressure is on your chin not your throat. There are very effective escapes I have learned in Brazilian jiu-jitsu but it involves doing a lot of mat work type sparring. The reason for this is that it is usually much easier to escape from chokes once you take your opponent down.