Step by Step Florals
Learning how to create beautiful flower vases with all flowers are one of the basic skills that every beginning florist should learn. I did a Rose Vase tutorial that showed step by step techniques for using roses with the thorns still intact.
You should separate flowers into focal flowers (the largest) secondary flowers (2nd largest), filler flowers (babies breath, limonium, or statice) and then greenery.
Don't feel locked into the same exact flowers as used in this tutorial, but use it as a general example of placement: