When I get new fish I put them in my quarantine tank. It is pretty bare compared to a full on reef tank with rock and corals.
So I make sure there are several large pvc fittings in the tank. Big enough so the fish can go inside them.
I also use a plastic cave I picked up years ago as a freshwater decoration. Fish seem to like to hide out in it.
Another thing I usually do is tape black ( or just dark) construction paper across the ends and front of the tank, leaving a couple inches open at the corners and top 2 inches.
If the fish can't see you as well, they will calm down faster.
For a first food I like to add live food such as live brine or Tigger Pods in small amounts. If it's moving most tangs will go after it.
When I switch to frozen food like frozen brine or mysis ( Hikari in cubes) I put small amounts of thawed food in the stream of a powerhead that is part of my qt tank equipment.
I also make sure there is no uneaten food laying around on the bottom of the tank.