Hi Dave,
Agree with the background comments. You need to choose something more neutral that isn't going to compete with the flower in terms of colour.
And if you're going to shoot the flower on a diagonal, IMO it looks better if the angle is more pronounced so that leads in from a corner of the frame.
The other thing is the DoF. It's very shallow in this shot, which isn't always a bad thing, but it looks like you have the focus on the buds behind the main flower. This has left the most interesting parts of the photograph oof.
If you're going to use a narrow DoF try to get the focus sharp on the main focal point of the shot - in this one the centre of the Lily at the front; or go for a smaller aperture to get more of the image in focus.