Here is a No-Gi variation for the Sneaky Americana (Keylock) I've been using from under the head. Using the shoulder to crack open their frame, can help me pry my opponents arm up closer to their head, where I can snag ahold of it to go for the Sneaky Americana. 

Be sure to insert the hand palm up so you can use the fingers to ply along the muscles of their arm and help you get underneath when they are trying to block it. 

Again, this variation I've been using in Brazilian Jiu-Jitsu (BJJ) in order to keep my position during the attack. If I launch my attack across the body, the more savvy practitioners will counter and push my arm away, or launch me over their body. 

A nice alternative to the keylock for more flexible opponents, is pushing the elbow vertical and then applying downward pressure to lock the wrist. 

The turn away: when they go on their side to defend the arm, we go for the arm closest to us to setup and armbar. If they begin to block that, it will create the opening we need for the Americana. If they block both, step the leg over the waist and roll them back into our guard to finish them from the back. 

Have fun with this technique. I've been enjoying it a lot!!!