The indicator for the standing guillotine defence is obviously if your opponent catches you in a guillotine choke. You flex your neck muscles, and catch their guillotine-ing wrist with your hand on that side, with your other arm reach over the top of their shoulder, so that the palm of that hand is facing down on their back, and when they try to apply the choke, move your feet around to the side opposite to the choke. Then, in a movement my Gracie Garage training partner Ash and I nicknamed 'Elvis-ing', because the movement resembles Elvis Presley's 'Hound Dog' dance moves (as shown in this attached image: 
), you kind of use your knee to collapse theirs from behind, while simultaneously putting downward and backward pressure on their shoulder and their back, using your arm which your earlier placed over their shoulder. As they start to collapse backward, you scoot sideways in the direction they are dropping, and crouch as they go down, so that you land in a kind of side mount, but you are still stuck in the guillotine. It's important that the hand you placed on their wrist at the start to prevent the choke from sinking in still remains there at this point. You now slide your free forearm across the front of their neck, and apply downward pressure in a paper cutter fashion, to force them to let go of your neck, at which point you attain full side mount with Gable grip. This is an image of Rener performing this technique, he is in the post-'Elvis-ing' stage, where he has already buckled Ryron's knee, and is starting to lower him to the ground backwards.
The hook sweep, shown here:
as you can see is a guard technique, for the indicator of your opponent standing up with one leg forward. You grab the ankle of that forward leg, put your foot on their hip on that same side, and with your other foot, hook in behind their other knee. Your hand on their ankle pulls, your foot on their hip pushes, and your foot hooked behind their knee pulls, and they have no choice but to fall back to the ground. At this point, you do a quick base get up, and begin to assess your opponent's response, as they may sit straight back up in order to get back up and continue fighting on their feet. If this is the case, then you can move quickly to pin them back on the ground before they fully sit up. Or they may remain lying on their back, with their feet up in order to kick at you, which are highly dangerous and extremely powerful kicks from this position. Depending on the situation, you could either run away to escape at this point, or work on passing their guard by catching one of their ankles and moving around it carefully. Catching someone's feet when they are kicking at you though is a dangerous game, so must be approached with caution.
Cheers,
- David