There aren’t a lot of things that are going to make you immediately more successful in Brazilian Jiu-Jitsu… But breaking the opponent’s posture is certainly one of those things. That is, if you can break their posture, you’ll make them more defenseless and more prone to your sweeps and submissions.
However, breaking the posture from Open Guard is never an easy task. Luckily, BJJ black belt Jon Thomas has some great principles that’ll make you improve in this task so much more. Just keep in mind that all these posture breaks have one thing in common: a collar grip.

POSTURE BREAKING PRINCIPLE #1: STAY AWAY

The first principle you’ve got to take to heart is to stay away from your opponent. What this means is that, if you’re really close to the other person, you’ll have an extremely difficult time breaking their posture and keeping it broken.
So, the next time you’ve got your collar grip in place, scoot back a bit. It’ll render the opponent’s defense weaker by a lot.

POSTURE BREAKING PRINCIPLE #2: FOLLOW ‘EM

If your opponent is already deadlifting their way out of your posture break, follow them. Don’t just keep your collar grip, as their posturing up will almost certainly break it.
Therefore, you should follow them through their posturing up. Then, once they’re upright, you should place your shin against their hips and use the bottom leg to push off the mats; thus bringing them down to the mats yet again, in the way that Thomas demonstrates on the video.

POSTURE BREAKING PRINCIPLE #3: USE THE COLLAR SLEEVE GUARD

If the opponent goes to break your collar grip, you should be ready to immediately establish your sleeve grip when they do so. Then, once you have this grip, you should get your collar grip once again.
The sleeve grip will make it much more difficult for them to break your collar grip, whereas you’ll use the collar grip to break their posture. Plus, using the now-established Collar Sleeve Guard can only go to your advantage.

POSTURE BREAKING PRINCIPLE #4: ATTACK THE LOWER BODY

If you’re simply unable to get that collar grip (maybe the opponent is too tall or they’re really successful at breaking your grips), then you ought to attack their lower body.
By threatening them with a lower body submission or sweep, you’ll make your opponent focused on addressing that issue first. To address it, they’ll have to lower themselves; which you can then use to set up your posture breaks yet again.