This is a complete new area for me and I appreciate every comment. The portrait was more a snapshot made indoor with an external flash bounced to the ceiling. The sky I had shot a few days before for no reason. I merged the shots, which I guess can be noticed easily, even though I tried to soften the edges (the original background was just horrible).
Still I do not think it is a really good picture! Well the young lady is beautiful, as well as the real and the painted flowers. Everybody who disagrees should know that it is my daughter! But this is not the point. I am biased and would like to understand how to improve the image from a photographic point of view.
Additional note:
Finally I have used Zahid's work, slightly tweaked (see comment below) and replaced the original!