painting roses

“There is nothing more difficult for a truly creative painter than to paint a rose, because before he can do so he has first to forget all the roses that were ever painted.” -Henri Matisse

I cannot finished my painting because I am not satisfied with it. It's my first attempt to paint red roses(usually I paint pink roses) and in a very big canvass. I took a picture and try the filters in PH CS if the lights and shadows were ok but I am not sure still, which way to go to finish it. I do my paintings now in my kitchen where I have really wonderful light-