If you buy a plant in bloom, you'll want to enjoy the flowers, but don't immediately abandon the plant on the coffee table for two weeks! It's been shipped and jostled about, so treat it nice. Place the plant in proper quarters for the daylight hours: provide appropriate light, temperature and humidity. Water it. Feed it. This will also help keep flowers fresh, since flowers last better on a happy, wellcared-for plant. It is perfectly all right to display the plant for a few hours a day, a couple of days a week at most without significant harm, preferably in the evenings.
Keep new plants isolated for a couple of weeks, in case there are unwelcome fauna. Of course, few of us actually practice this quarantine period! At the very least, inspect new arrivals well, especially leaf axils and undersides of leaves. Bugs like aphids and mealies also like to hide just behind open flowers.
Bud blast—having the buds suddenly shrivel, yellow and drop from the spike—is unfortunately common on newly purchased plants, especially dendrobiums and phalaenopsis. Stress from shipping, irregular watering during a show, bruising, and exposure to dry, chilly air all may cause unopened buds to die. There's nothing you can do once that damage is done, except take good care of the plant so it will bloom for you again next season. (Sometimes the spike makes the effort of some new buds...sometimes not.)
Don't mist flowers, even in a very dry room, since this may cause spotting. And be careful not to dislodge the sensitive anther cap at the very tip of the column, as this will mimic pollenation and the flower will wilt. (Go ahead, try it and see.)
Finally, don't be afraid to just cut the spike and enjoy it in a vase. This will give your plant an easier adjustment period, since it won't be burdened with a spike. Newly-purchased or young phalaenopsis shouldn't be forced to make new buds on an old spike, so cut the spike entirely off once the existing flowers are finished.
And oh, yes: when buying a plant online or at a show, remember advice from a Floridian or Hawaiian greenhouse probably needs amendment if the plant will live in a New York flat! If a grower from a warm, sunny climate recommends "shade" for a plant, it might very well prefer plenty of sun here in the northeast. Trust but verify!