In this video I show a basic escape from the back called the Monkey Grip.
As you can notice from the video the grip is not symmetrical. This is the first video in the two part series where it shows how to defend to the side with the hand contoured to the neck. Check back in to the channel to see how to defend to the other side.
Most importantly I discuss the concepts of back escaping. There is no more important concept than "if my back is on the floor then my opponent is not on my back". If you keep repeating this to yourself you will be headed in the right direction. When in doubt get your back to the floor!
It is also important to note that the hand that is reaching up and going over the head needs to be slightly tucked forward. This hand is separated from your body and can lead you into some problems with armbars. If you know about this danger and account for it with your body pressure then you should be ok.
Make sure that after you have turned the trunk of your body and placed your back on the floor that you keep your hips heavy on your opponents leg. This will give you a little bit of control over your opponent and make it difficult for them to transition to mount. Keep in mind this will not STOP them, just slow them down. It is important to control that leg at the knee so that your opponent can not mount.
Once you have control of that knee it is important to bring your inside elbow to the floor (regardless if you're coming up in Side Control or Guard, so that you can turn your body. So many times I have seen lower belts trying to turn in fighting their opponent and their own body. If you simply move that arm out of the way it will be very easy to turn up.
When coming up to your knees it is important to maintain control of that knee or you may be susceptible to armbars and triangles. If you have the option it is a good idea to push it to the floor on the other side (not really showcased in this video) so that it locks the hips in the opposite direction.