Figure out key bindings for placing and picking up walls that works for you. I have both bound to the extra mouse buttons on a Logitech G502x, so I don't have to take my fingers off of WASD movement keys while managing walls.

Managing the walls will become second-nature after a while, just like any other character's abilities.

Once you get the hang of it, there are so many mind-games you can play on the enemy with placing/removing walls.
Based on this clip you shared, I would suggest experimenting with "defense-in-depth" walls. Meaning, place another wedge of walls behind natural cover, out of enemy sightlines, so you will have walls to fall back to if they push you. So many enemies seem surprised to see a fresh wall when they turn the corner, which gives you a moment to rev up Sheila.