The Ezekiel is a strong and simple submission that can work well if set up correctly. In this video I show a very simple set up that works well when combined with the Triangle from mount.
Make sure you keep your base low and your head between your opponents head and your Ezekiel setup. This will make it very difficult for your opponent to know what you are doing.
Make sure you dominate that arm and truly try to make space between your opponents arm and their rib cage. The further you take their arm out of position the more threatened they will feel. Even if your kimono is tight like mine is in this video your opponent will find a way to get their arm back into position next to their body. It is very unnatural for us to feel our arms get moved like this and it is normal to try and get it back into the game.
I also address the importance of taking that slack out of the kimono after you have already cleared the neck with your fist/hand. It is important to do that as it will move the fulcrum of the choke and multiply your force even more. Simply move your arms until that fabric touches their neck and then add the force.
Posting the leg gives you more force for the choke and it also gives them something to grab even though it really has nothing to do with the escape from this move. Make sure you maintain that top position. If something does go wrong and you do not finish simply leg go with your hands and do the Break Dance move that I show in an earlier video.