please suggest how this might be improved. thanks.

Petals.

Oh, you got me there. lol, hmm, fill the frame! =P No, i have absolutly no idea, anyone else wanna take a stab at it?

...i guess in every case, filling the frame isn't the bestest.

Good question. While you've definitely filled the frame, I think you've probably gone overboard on that aspect. Perhaps back off just a little to add some of the stem. Also adding another object, such as a bee to add interest. Also looks like you've got direct sunlight. Try shooting on an overcast day where the light is more even. Always be mindful of your background. Your background on this is pretty good. fairly blurred however, it could stand to be more even (less clutter).

I'm curious to know why you want to improve this? Are you not satisfied with it?
Look at other flower shots of other peoples to see what you like. What do you like about them?

I don't think this needs to be improved Jen. Do you think there is a problem or are you curious? I am ;=)