Thoroughly clean your vase. Rinse well.
Add warm water to the vase about 2/3 full.
Add flower food to the vase or a homemade flower food combination. (see above)
Trim the bottoms about 1/4 inch of each flower stem.
Remove all foliage below the flower heads.
Begin to arrange the flowers starting with larger multi-stemmed flowers, then fill in with smaller and single stems.
Finish with filler plant material.
Turn the vase around and adjust from all sides.
Place your vase in a spot that's cool and dark until ready to use on the table. If possible, you can set it in the refrigerator.
After about 5-7 days, check the flowers and water level. If there are some that are drooping or fading change the water and add in more flower food.
Continue to check the vase daily removing any flowers that are spent. Rearrange the remaining flowers and/or consider moving the remaining flowers into a smaller vase.