I try to make a boutonniere as interesting and unique as I can. Adding a variety of fresh greenery keeps the boutonniere simple, yet adds lots of different elements so the design isn't boring.
Myrtle is a great addition. Once single stem has a lot of laterals and can make several boutonnieres and corsages. It has a pleasing aroma and the smaller leaf size is well suited for smaller designs.
Strip off the bottom leaves so you have a bare stem. You can tape this directly to the boutonniere this way if you wish.
I prefer to wire all the different flowers and sometimes greenery in order to have more flexibility. I can bend a wire any direction I want the stem to go without fear of breaking. I also strive to keep the bottom stem of my finished boutonniere as slender as possible to avoid ugly bulkiness.
Make a hook with a 22 gauge florist wire.
Slide the hook into the myrtle stem until is is caught around the stems and lowest set of leaves.
Pull down until tight. Leave just a short piece of the actual woody stem - snipping off the rest of the greenery stem with wire or bunch cutters.
Use florist tape to attach the wire to the shortened stem of the myrtle.
Place the newly wired stem so that it stands a little higher than the top flower of your boutonniere design.