The above applies to double rifles only! You pull the trigger that fires the choke you want for the shot you are takeing! I set my double trigger shotguns up if I have screw in chokes with the right barrel the tightest choke if I'm pass shooting, or shooting in-comeing birds, This way if a pair is coming in, I fire the tight barrel (RT barrel) at about 35 yds, and fire the more open barrel as the other bird slides in another 10 yds or so, before he can turn.

If I'm walking up birds that flush from the weeds, then I fire the open choke first, then the tighter barrel as the bird is getting farther out! Never us a double trigger shotgun, or rifle with a finger on both triggers!

the right barrel on most double shotguns is the tighter of the two, I like it that way, because it is the same as the order that is supposed to be used with a double rifle.

As others have told you, practice, practice, practice, and it will come!