+1 on the hip out. I LOVE invisible collar. If your legs are long enough, try working the variation Eddie shows for getting it extra tight (i.e. grabbing your right foot with your left hand). My legs are crazy long and I find I can often tighten it up even on smaller guys.
One thing that helped me was settling into a good solid chill dog first. I usually double bag to chill dog and make sure I've got the neck fully cleared and my forearm deep into their collar bone before I transition to IC. I like to keep the double bag while I bring my right leg up; it keeps it really tight but it requires either a LOT of flexibility or legs long enough to pull it off. Either way, make sure your right leg is driving his left arm across your center. The further you can get his arm in 1) the tighter your IC will be and 2) the better the arm bar option should you not be able to tap him with the IC alone.
If his elbow is already to the center of your abdomen, keep it there with your leg squeeze as you bring your right leg up. He needs that left arm to take the pressure off of the IC submission and to create space so getting it toward the center is huge. Sometimes when I'm bringing my right leg up I swing it wide and kind of pop my hips so that it pushes his elbow across much like in crackhead control.
After I get the arm across and my legs are locked up tight I tip onto my right side so that my right thigh is parallel to the floor. Tipping onto your side takes away his base since he no long has a left arm to post with. The variation I do here is: cross your ankles so that your right ankle extends a little past your left. Release your grip on your left ankle and slide your right hand up and grab your RIGHT ankle with the same wrist-to-ankle grip you had; keeping your ankles crossed. Now when you pull down and drive your elbow into his collarbone, you are also assisting your right leg squeeze. You can further assist the squeeze by hugging around the knee with your left arm and pulling down on your right hand with your left -- again, helping to drive the elbow into his collarbone while increasing the leg squeeze.
Hope that helps; sorry if it's confusing. I always find it hard to interpret written descriptions of techs and I think it's even harder to write them!