At this point, I’ve been training on and off for 2.5 years. For what it’s worth this is what I do for bjj defence. I’ve been focussed on this stuff and it’s been working pretty well for me. Everything I describe below has worked for me for gi, nogi, and mma.
1. Keep your hands up close to your chest with your elbows tucked in. It doesn’t matter if you are on your feet or on your back. Protect your head and face from strikes. If someone knocks you out they can have their way with you and none of the advice below will do you any good.
2. Grip fight like a mofo. You have to intercept their hands and not let them establish their grips. If someone grabs your lapel, strip it right away. If someone grabs your wrist or sleeve, hand fight. If you let someone control one of your arms and latch onto your torso, you’ve already begun to lose the exchange. I learned this from taking 2 or 3 judo classes.
3. Don’t settle for bottom. If someone is halfway to taking you down, use your energy to defend the takedown and stay on top. Use whatever takedown defence you know. If you end up on the bottom it’s going to take even more energy to defend and get back on top. I got this from Niko Han. It really changed my grappling mentality and performance.
4. Never ever lie flat on your back. As soon as someone takes you down or passes your guard, get on your side and face them. On your side as in 90 degrees to the ground. Block the incoming cross-face using your closest hand while keeping your elbow tight to your body. Fight to block it. It’ll make your life much easier. I’ve read many articles to find the best posture for this, still experimenting.
5. If you are wearing a gi, your opponent mounts you and grabs a cross collar grip for a choke, turn your body towards the elbow of the attacking arm. I got this from Saulo Ribeiro’s book and it works amazingly well! When you turn your body towards that arm it takes away the angle of the choke. You have to do this as soon as you see them go for the grip. If you are late they will get their second hand in and you are done.
6. Whenever you feel a hand or forearm touch your neck, abort everything you’re doing and grab their attacking hand with a two-on-one grip. You have to respect the choke. It doesn’t matter what position you are in or if you are in the middle of your own set-up, abort everything and defend your neck. Even if you end up in an inferior position, you are still conscious and in the fight. Anytime I grab a two-on-one grip, I can use it to set up an escape. Another gift from Niko Han.
[Update] My instructor Ritchie Yip showed me that if I grab the two-on-one in any position, i.e. bottom cross side, bottom mount, I can disrupt the offence of my opponent. They will eventually get frustrated and give me space in order to grip break. I mostly grab the two-on-one when I'm in four-point or someone has my back. Now I'll experiment with it from everywhere. Great tip.
7. Keep your elbows and forearms tight to your body. If your elbows are flared out your opponent will arm drag you for takedowns, use it for upper body control, or arm lock you. Some people call it T-Rex arms or prayer position. For the last few months, I’ve been doing the prayer position but clasping my hands together with a gable grip. This gabled prayer forearm posture has been money for me.
If someone manages to grab one of my elbows or forearms, I can use the strength of both my arms to reel it back in. If someone manages to set up an armbar, the gable grip gives me an extra moment to react with the appropriate escape. I also pre-emptively hide my elbows by pinning the closest one to them, down to the ground. From this forearm posture, I can keep my hands clasped together while I dig for elbow knee escapes, bridge and push off my opponent, roll to four-point, escape from knee-on-belly, etc.
Basically I’ve been moving my body like I don’t have any arms, it’s been working well for me and hasn’t hindered my game at all. I automatically return to this forearm posture even when someone attempts an armbar or triangle from their closed guard.
8. When some takes my back, I assume my forearm posture and defend any incoming chokes, then I get into what Saulo Ribeiro calls the Scoop. I slide my body down towards my feet and spread my legs out for base. If I’m too far down my opponent cannot choke me and my arm posture prevents any armbar attempts. From there I can work on my escape.
Here’s a video of the Scoop:
9. If I end up in four point, I don’t wait around for them to attack, I quickly get back on my feet at which point I can back away or drive in for a take down. In pure grappling matches, a lot of people stall and rest by turtling. If you turtle in a real fight your opponent can end the fight by throwing knees to the back of your head. Interestingly enough, most grapplers I’ve encountered don’t know how to react to this. Yet another gift from Niko Han.
That’s all I know about defence for now. This doesn’t cover escapes, which is something I’m been working on as well.
I'm really enjoying Saulo Ribeiro's book, Jiu-Jitsu University. I've been testing his defensive postures in training and they are working well for my game. I also like his approach and priorities to building a solid grappling game: defence > escape > positions/passing > submissions.