Well, shoulder/head/neck control is a given if you have a free hand. This is ALMOST Kaiten Nage, from Aikido. Unless you are talking about pulling the shoulder down with the grabbing hand. Which is also a given. Soooo easy. Heck you can do it with just a pinky finger looped on thier sleeve. It's been so long since I have done stand up sparring with a gi on I had almost forgotten how absolutely fan-fucking-tastic this technique is.
IMHO one good tug and that is all you need. Your free hand should be punching them in teh face. I don't discount the round kick to teh face either - because that is what created my appreciation of this technique. That and the black eye.
But from a stylistic perspective that second hand should be punching or getting ahold of the neck for some crapple. If you can reach behind it to reinforce the arm control and begin your onslaught of punches/kicks/knees, than you could grab thier neck and bring them to a kinder, gentler, and more peacefull state of being by choking them the **** out.
The arm drag is my favorite takedown right now. This is what I do... its like a game.
1) Try to drag using my right arm...
2) They turn in to square up to me...
3a) Shoot a single to a double on their right (on my left) leg.
3b) Try to armdrag using my left arm.
I usually try 3b first, because it sets up the shot better. If they are more worried about getting their arm back then its easy to get the leg. Now if need be, I keep going through this over and over and switching 3a and 3b until I get what I want.
I am running tournaments each weekend at my school, and we are making short highight videos each week. If you watch this one, http://aggression.tv/week3_divx.avi , You will see me drag my brother in the end (he tries to pull a flying triangle as I am driving with the takedown). Its dark for the armdrag, but if you watch it a few times you can make it out. I armdrag him and shoot my single to double, keeping his right leg (on my left) off the ground, and he pulls for the flying trianlge but has no chance because I have his leg controlled.
That was a LONG day. I think i bruised my rib, which sucks in itself, in my 2nd match. I then had the most painful tournament experience as I had 7 more matches for the day. I ended up winning all my matches for the day by submission, but they werent all pretty.