Excuse me, how to make this flower arrangement look better?

First of all, the length of the main branch of the flower should be 1.5 ~ 2 times the container inch method (that is, high caliber). Then, because your container itself has some patterns, I suggest you choose a lighter peony flower. Such as white or pale pink. Later, because you are easy to have a beautiful arc, you can highlight this arc as much as possible when arranging flowers, don't cover it with flowers, and you can use iron wire to realize the arc in the treatment of flower branches. Type c or z is better. Take a completely open peony as the main branch, and then choose a peony in bud as the guest branch. Vertical or inclined is ok.

There are no particularly suitable pictures, but this can be used as a reference.