Hey katrina,
Cool image! Great that Marco critiqued it! He's a cool guy and a great painter.
Now I'd like to throw in my 2 cents (of course!). There are a few things that are distracting me in this image which I wanted to mention. These are totally subjective so take it as food for thought and not concrete directions.
The first Thing you might address is the overall color balance. Color is great! Too much color hurts my monitor! This one has fully saturated reds with fully saturated greens which will vibrate and will be screaming when put together. Might I suggest going analagous with the fairy and keeping her in the yellow/orange/red family?
Srokes: The top half of the image seems like it's painted much tighter than the bottom half. I love brush strokes, but they need to be consistent around the image. At first I thought the bottom of the image was actually pixelated or low resolution. I'd tighten up around the boy and let the loose brush strokes happen around the edges and in the negative space llie you did for the backgorund.
Light: Like the color, this one has light everywhere. You might want to control that a bit more and guide the viewer. I added a shape to the glow and backed off of the hot spot on her dress. Then I lightened his face so it's easier to read against the darker dress.
Lastly, you want the red to be just part of the fairy and by having the ground be the same red it takes away from the fairy a little bit. So I changed it to an ochre color.
Again, take these comments as just rough ideas. To sum up, I'd pick the spots where you want to go saturated and where you want to go contrasty and really control them. If everything is saturated and contrasty, it makes the viewer a little confused on where to look and can make the image overly loud.
Here's a quick paint over keeping that stuff in mind. Keep up the good work. I love seeing all your explorations!