Great photo! I like the contrast between the white and green, and the composition is also wonderful! The way you positioned the flower gets the viewer's attention right away, though I think you could've zoomed out a little more. The angle is lovely, though!
Are you able to adjust the white balance on your camera? Something doesn't seem quite right with the colors here. On the bottom petals, there seems to be a blue tint, and in the middle it's more warm and orange-tinted. I found this to be a little distracting, but also an easy fix. You could try Gimp, a free editing program, to mess with the color balance and select certain colors to work with. However, it was probably just do to the lighting
The shallow depth of field works well with this photo, and also brings the flower out from the background. I do think the focus could be sharper, but nice work!