Wholesale flowers are shipped to keep the heads as protected as possible. Some flowers, like these Asiatic lilies, have protective netting over the heads that you remove when you cut and place into water buckets.
Make sure the heads are not leaning into each other, but have plenty of room to open fully.
Lilies have pollen in the center that needs to be removed. Otherwise it will turn into a deep yellow that can stain flower petals, carpeting and clothing.
You always look for the next "holes" that need to be filled in the design.
The lilies will need a full day or two to open. Don't be afraid to use the buds - they will continue to open in the design if they have enough water.
Step back and look at your overall design to be sure you are distributing the flowers equally.