Both of them's too big, make the canvas size smaller.
For the first one, you need to work on giving more depth to your BG and the BG's really dull and there are lots of unused space.
The white bits don't help either. Her shoulder looks weird, as if a part has been cut off, but I'm not too sure about it. Work on your text too..
Second one..the hair needs some work (the left side) and blend the render in, that white thing around him really annoys me for some reason. Good try though and read some tutorials, they'll help you out lots.