For longer life, cut flowers early in the morning; use a sharp knife or scissors and immerse the stems immediately in tepid water. If the stems are woody, scrape a little bark from the base to help them absorb water. When buying cut flowers, choose blossoms that are just beginning to open.
Let the stems sit in deep water for several hours. As you arrange the flowers, clip off the bottom of each stem and strip any leaves that would be under water in your vase. Be sure your vase is scrupulously clean.
To hold flowers in place, use florist’s foam or a pin holder and florist’s clay, available at flower shops. Use the clay to anchor the pin holder to the container. If you are using foam, soak it for several hours until it is thoroughly wet, then pack it tightly into the vase so that it doesn’t wobble.
A flower arrangement should have an overall sense of balance. The balance maybe symmetrical, as in a round centerpiece, or asymmetrical, as in a scheme of three handsome branches and a single spectacular blossom.
Scale and proportion of the flowers should be appropriate to one another as well as to the setting and container. Combine a variety of colors, patterns, and textures within a unified whole.
Unity might be achieved by massing similar flowers. Or a few dramatic flowers could provide a focal point to unify several varieties: first place a few stalks to establish the overall shape, then add filling material, usually greenery and light, relatively inconspicuous flowers. Finally, arrange the most dramatic flowers strategically at the heart of the bouquet.