When I first started training jiu jitsu, I decided to pick one simple submission and drill and use the heck out of it till it was second nature for me. Guess what I picked. Yep, cross-collar. Looks so simple, right. I usually attempt it when someone is in my closed guard. Ask anybody at my gym and they point at me as the cross-collar guy. Not that I'm that great at it, but boy, do I try almost each and every time to get this submission.
I've been training a little over two years now, and I can say I'm barely getting decent success at it. I don't remember who said it, but I remember reading some Gracie guy I believe who said cross-collar is one of the simplest submissions, but also hardest to master. I wish I read that couple years back, so I would have funneled my energy into some other submissions.
The cool thing about cross-collar from closed guard is, it involves little risk. You're not exposing yourself in anyway, no need to open the guard. However, if you go at it hard and not get it, your forearms are gonna be so damn tired, your grip strength will be reduced to that of a 5 year old girl's for a little while till you recover.
Like anything else in life there are tricks to get this submission as well. First off, don't go for it each and every time like I had been doing for a long time, it becomes too predictable, and all your opponents need to do is a little posture, and wait until you get tired. What I've been doing more recently is, getting the first grip nice and deep first and don't even try to sink in the other hand, and act like all I'm trying to do is control my opponent and fake a scissor sweep. My real goal is luring my opponent to try to pass my guard while I still have one grip on the collar. So, if my right hand has a grip on the right collar of the guy, I lean on my left side about 45 degrees, faking the scissor, at which point my opponent presses his body weight on my right knee and keep their head low, which is what you do passing guard right? And that's my moment to bring my other hand to the other collar or right behind the collar grabbing the gi, and choke. This is a riskier strategy, but it has been working for me better than just going for it straight from closed guard. I also remember seeing a video of it, and will be posting that video as soon as I find it.