You need stronger colors for one. Make the intensity of the color higher and add more. Make sure they are bright, and don't use any dark colors(that will kill this piece. Since you since she brightens the day that make sense. Another thing I would suggest is to Vexel a cartoon version of the sun. It will add to the flowers effect. Last, add a border, preferably a dark color, this bring the focus on the main piece. Overall, nice work.