Most online florists have a wide variety of modern flower arrangements ready to order, although some would warn you that same_day delivery might not be possible, therefore you should confirm with your florist before you buy these flowers online.
Next, fill your "real" vase about two_thirds of the way with warm water. Make sure it doesn't leak. Add flower food if available. (Follow the instructions on the packet.) Place a few of your larger blossom flowers in the vase and step back. This will give you a better idea of how to proportion your bouquet. If the stems are too long, simply cut them shorter. If they are too short, try a different container, or add pebbles or marbles to the bottom of the vase to elevate your flowers.