Professional florists usually create a hand tied bridal bouquet by holding the stems in one hand, rotating them around, and adding more stems in a crossing 45 degree angle.
They generally do not stop to tape each individual flower head into place. This is much quicker, but if you are unaccustomed to this method it can be rather frustrating, as the flower stems can quickly become hard to handle and rather bulky, causing flowers to slip and slide out of place.
Taping each individual rose into place doesn't take long and you don't have to worry about hand fatigue.
Cross your second rose across the stem of the first rose as shown below.
Take up a piece of your pre-cut Bind It tape.
Place the tape about 5" below the flower head, pressing your thumb against the tape and the rose stem, holding it in place. Peel off the protective cellophane layer.
Pull the tape outward and wind it around the flower stems, so that the tape stretches and adheres tightly to itself. It seals very tightly, yet doesn't harm the flower stems in any way.
In the "V" shaped space between the rose heads, place another stem of myrtle.
Tape it into place as shown below.
Here is a side view of the roses and greenery after being taped into place.