Pretty much the same way you would acclimate any new fish, anything different between the water they are already acclimated to and the water they're going into needs to be handled gently. (temperature, pH, hardness, salinity etc etc) Lights out will help any fish feel more secure.
Have them check the pH of the tank at the store, and then compare it to your pH at home...if they're drastically different then a drip method is usually best. Setup some airline tubing from the tank into a container with your new fish and their original water...then set it up so the pH will change VERY gradually. Anywhere from like 20 minutes to several hours depending on how different the water is.