Keep flowers and plants out of direct sunlight and away from air vents that blow air on them.
For flowers, it is best to fill the vase to the very top as soon as it arrives and to refresh the water daily. You should be able to tilt the vase so that most of the water will pour out. Then refill it with fresh water. If one flower shows signs of wilting, you can just simply remove it and enjoy the remaining flowers.
For green and blooming plants, wait to add water until the soil becomes dry. When watering, soak the soil and then pour off or out any excess water. If you ever want to transplant to a bigger pot, just wait at least a few weeks so the plant can adjust to their new environment before they undergo major changes in their pot and soil.
For orchids or succulents, wait about 10 days between watering and provide only a small amount of water. Orchids and succulents thrive in a dryer environment! Overwatering is a very common way to cause the orchid to be unhappy!