Andrew, I’m an amateur user of Photoshop (CS3) and think the image you present is a good first effort; however, there are a couple of things you might like to consider.
The plane is not sharp, so would adding a little motion blur conceal the fact?
The background is sharp, so as an alternative to the plane being blurred would motion blur applied to the background give the effect of panning? Thus taking the eye from the fact that the plane is soft.
The plane is above water, would it not have a reflection?
As Ben says if the plane was smaller in the picture it would look a little sharper.
Keep playing, experimenting, watch loads of tutorials
At school I was told to “read and inwardly digest”, this was never truer than with photography and Photoshop.
Rhodese.