Select the flowers for the arrangement. Durable choices include roses, birds of paradise, lilies and gladiola.
Choose a tall vase at least one-third as tall as the flowers. For example, use a vase at least a foot tall to display 3-foot-tall flowers. Clean the vase and fill it to within 3 inches of the top with room-temperature water. Add cut flower food according to package directions to help keep the flowers fresh longer.
Use garden shears to cut the tall flower's stems at a 45-degree angle. This exposes more stem to provide the flower with plenty of water and nutrient to keep the tall flowers from drooping.
Place the long stemmed flowers in the vase one at a time. Use an odd number of flowers, such as five or seven. Large dramatic flowers, such as birds of paradise, work well by themselves. You can add tropical-looking foliage such as calla lily leaves. Place the tallest flower near the center and angle the stems of other flowers to hold it in position. Crisscross the stems by inserting the other flowers at an angle. For example, place a large rose at the center and cross two others to the right of it, one facing toward you, the other facing the opposite direction and repeat on the left of the central rose. Repeat this crossing of stems around the central stem until the arrangement is as large as you wish.
To create a dome-shaped arrangement, cut some stems 2 inches shorter than the central blooms and some 4 inches shorter. Use the taller stems closest to the central flower group and the shorter stems toward the edge of the vase all the way around.
Add foliage, if desired after the main flowers are in place. To create a fuller-looking bouquet, add filler flowers last. Filler flowers are small flowers such as baby's breath or St. Anne's lace. Insert filler flowers between the larger flowers.