This can be learned in Shaded Woods. From the Ruined Fork Road bonfire, take the foggy, rightmost path. Hug the left side of the area, looking for a little inlet that leads to a pile of debris. You can actually speak to the skull atop the pile - it's the Head of Vengarl, and it can teach you a new gesture if you keep talking to it.
To learn this gesture, you must first join the Blue Sentinels covenant - see our Dark Souls 2 covenants guide for more info on that. Once you join, speak to Blue Sentinel Targray to learn this.
When you open the Undead Lockaway bonfire in Huntsman's Copse, speak to the man inside. After a few exchanges, he'll teach you the gesture.
When you enter Undead Crypt, move ahead until a voice warns you against producing light. Take the stairs in this room to find a small alcove housing Grave Warden Agdayne. Speak to him enough, and he'll offer to teach you this gesture.
To learn this, you must proceed through Dark Souls 2 until you acquire the Ashen Mist Heart. This allows you to step into the memories of the trees in Forest of the Fallen Giants. We're headed into the Memory of Vammar. It's found within the tree near the Cardinal Tower bonfire.
Now head down the tunnel and speak to Captain Drummond. After enough times, he'll give you the option to learn the gesture.
You can encounter Bernhart a few times during the game - first after de-petrifying Rosabeth, and again at the Central Castle Drangleic bonfire. Speak to him enough times, and he'll teach you the gesture.
You can learn this from Straid of Olaphis. in The Lost Bastille, but getting to him is a bit complicated. Start from the Servants' Quarters bonfire, head outside, and follow the walkway into the next tower. Head up the spiral steps here, then through the wine casket room into the room full of clay figures. Head up the stairs here, then up the following set to find a bunch of mummy enemies near some jail cells. Take them out, then look to the left cell to spot a petrified NPC - this is Straid. Use a Fragrant Branch of Yore to restore him, then talk to him to get the option to learn the gesture.
"Praise the Sun"
Though this gesture is associated with the Heirs of the Sun covenant, you can learn it without actually joining. For that, you must first find the Altar of Sunlight; see our Dark Souls 2 covenants guide for more information.
From the Central Earthen Peak bonfire in Earthen Peak, head up the stairs and into the hall. Step out onto the windmill balcony and move left to meet Laddersmith Gilligan. Talk to him, and you'll have an opportunity to learn the gesture.
"This One's Me"
When you enter Drangleic Castle proper, head up the stairs and speak to Chancellor Wellager. Eventually, he'll give you the option to learn this gesture.
You'll need to buy the Ring of Whispers from Sweet Shalquoir in Majula for this. From the Shaded Ruins bonfire in Shaded Woods, head up the slope and turn left. Enter the crumbling building, go downstairs, and exit to a small, sandy area. Out here is Manscorpion Tark, who will only talk to you if you're wearing the Ring of Whispers. Do so a few times, and he'll teach you the gesture.
To learn this gesture, you must join the Way of Blue covenant - see our Dark Souls 2 covenants guide for more info on that. Once you join, speak to Saulden to learn this.