This is first time for me to do a paint over so I'll give it a shot. So I like the idea for your piece, but I would say the biggest thing is your lighting. You have it lit all over the place. Your background on the lower right suggest the sun is back lighting the trees, but the tree on the left suggest the light is coming from right. Then your figure suggest the light is coming directly from the left because you lit her arm that is holding the bag as well as the bag itself. A huge portion of her left side would be in shadow. Especially if she's deep in the forest like you have her here. And then some of the apples, because of the highlight, looks like the light is directly coming from the camera straight at it. I also think the reason why it looks dull is because you have a similar color temperature all over the place where you are using pastel-like colors, even in the shadow. So here is a quick and dirty paint over I did using mostly adjustment layers and some painting:
This was done quick and dirty, but the main takeaways is to have a clear separation of light and shadow. You can use lighting as a composition tool to focus where our eye is supposed to be looking at. I also added a foreground element as to give more depth so you have foreground, midground, and background. You don't have to specifically have a bush there, I just put it there so there is a better sense of the space. I then put a bit of mist towards the base of the trees to knock back the trees because when I used the adjustment layers it made it super dark and it was popping to the front.
Something that can help is to view your image in black and white and zoom out to make sure your values are working. Last thing, because I did this quickly, the image looks a bit fuzzy. I would say that's something to just watch out for is making too many elements in your image blurry as it can be distracting. I know this was kind of long, but I hope this helps!