I'm alway tempted to fiddle and do things when I have a new tank but I think it's best to stay hands off as much as you can. And when it's necessary to do anything, try to do it calmly and sedately. As silly as it sounds, whenever I enter the room with my tanks I try to make them aware I'm coming in.
Cutting out any bright light is a good idea, I always try to make the light dim in the room, but haven't personally used a sheet before.
Create lots of water surface movement and agitation so that oxygen levels are as high as possible. Either move the outlets a little, add an extra powerhead/air pump, or drop the water level a little to expose the outlets more.
I disagree with Catfish2012, in that you should try to get it feeding asap. I like to have veg like sweet potato and courgette/zucchini already waiting for them, and then once they settled into a hiding place, scatter some wafers/pellets/granules of dried food as close to them as you can. To be extra accurate I use a tube to direct the food, usually a spray bar I hay laying around. But the precaution with feeding and them not eating it is to keep on top of removing it as to not deteriorate water quality.