alot of the ways ive seen the Omoplatta done are sloppy. the way it is shown in Royler and renzo's Bjj theory and technique is pretty crappy.
none of them lock the figure four around the arm before moving to grab the belt/back. They simply turn and sit up.. which is the easiest thing in the world to escape.
the way i was shown. Is swivel to the side parallel, lock the figure 4 around the arm, grab the belt keep tight. scoop your hip out and kick your leg that is trapping the arm forward and toward the ground. Sit up, turn feet back and lean onto their back toward opposing shoulder.
like is shown on
http://www.abhaya.ca/technique.htm....... but i think the site is down now.
this isnt bad but also not closing the figure four. .. but is better then renzo and roylers books way
http://www.bjj.org/techniques/jacare/umaplata/
same thing here, not bad... but i think they should close the figure four to prevent escape a little more.
http://www.bjjfighter.com/techniques/gi/guard/Gi_omoplata[1].html
I cant find an example of someone closing the figure four... maybe im just wrong but its how i prefer it.. in step 2 on this one is where i would lock the figure four, or "triangle" the arm. So that i could get better positioning then continue with the move.
http://www.lockflow.com/article_view.php?id=39