Omen's one-way smoke guide in Ascent Vol.1
1) Mid market to Mid plaza one-way smoke This one-way is useful for defending mid market against a push from Mid or a retake. Jiggle the smoke back and forth until you see the greenmarker suspended on the wall.
2) Mid cubby to Mid catwalk one-way smoke This one-way can be useful if you're holding Mid cubby and expect the enemies to push from Catwalk. Stand on the box and place the smoke into the wall as shown. There's no marker to follow for this smoke, so it'll require some practice.
3) B main to B lobby one-way smoke This one way can be great if you want to set it up before the round starts and aggressively push into B main. Jiggle the smoke back and forth until you see the green marker suspended on the wall. Make sure you pull your cursor high enough above the green marker, otherwise the smoke will fall to the ground.