I support the omoplata route, however, I would say it is rather low percentage as a submission but awesome for sweeping and transitions. Each time your triangle begins to fail, pay attention to what is happening.
- If they posture up really hard, push off the mats and take the sweep into a mounted triangle
- If they stack you, hook the leg and sweep them over for a mounted triangle...lol
- If they hide their arm under your butt, feed your arm into the space between the opening of the elbow and your butt and take the armbar using your head and shoulder to trap the wrist and your two hands to apply the pressure to the joint OR take the kimura for a sweep or sub
- If they don't fit in your legs, learn to 'hide the shoulder' while cutting your angle
- If they try to pull out, switch to the traditional armbar
*Most importantly, learn what YOU are doing WRONG to begin with. Study Ryan Hall's triangle series and you will have a better conceptual idea of your shortcomings.