Painting Water

A common mistake I see in students' work when painting water is to paint hard stripe-y lines all the way out to the horizons.  If you really study the water, the ripples closest to you are the ones where you can see the shadow side of the little wavelets. 

 Gradating the water so that near the shore, the water appears darker and a bit warmer because you are looking down at the bottom where the rocks are warmer.  The reflection of the sky happens out closer to the horizon.  Gradation also suggests the softness of the water.  Stripes make water look like concrete.

And finally, reflections.  Again avoid stripes that start right where the boat or object meets the water.
Define the ripples at the edge of the reflection, not in the middle.  As you get further down, then you can start spacing the ripples again.

Also, study the reflection to see if it is lighter or darker than the object being reflected.  A white boat in shadow will often have a darker reflection.  This also will determine the order of painting.