During the summer months, it is lovely to get out and about, and few locations are nicer than the bank of a lake, or pond, or a canal. Not only are you surrounded by lovely landscape, you also have that landscape reflected in the water - a delicious subject to tackle.
However, dealing with reflections in water does require a bit of careful handling, so here are a few tips to help you on your way.
Reflections are generally darker nearer to you, and lighter further away. This is because the water which is further away from you is being seen at a flatter angle to the sky, and therefore the sky will "lighten" the surface of the water. When you look down into water, colours and tones are stronger.
Also, a good rule of thumb to remember is that generally, all tone is less intense seen in water...lights are darker, darks are lighter. Colours are more muted than the landscape around you. The Venice canal pic above shows this, I feel. (although I apologise for what looks like a bent building...camera parallax problem...just look at the reflections!)
Half close your eyes to cut out detail, and look for changes in large shapes from front to back, as this will help with the impression of recession. Running water will distort shapes - study the water for a while to see if you can see any kind of pattern. Choppy water, as in the top Venice pic above, will break up reflections - notice how the poles are reflected but their reflections are broken up by lighter "surface" ripples and eddies.
SURFACE OF THE WATER
Reflections are cast onto the surface of the water, so it is tempting to simply paint an upside-down version of what is on dry land - using horizontal marks or strokes , because the surface is, after all, horizontal....but .....
In fact, your reflections will work far better if you use vertical strokes -this will still convey the flat surface of the water - or try to avoid any sense of directional stroke for the reflection, keep it as a flat shape - and then you can hint at the water's actual top surface by picking up ripples, or lights, as small horizontal marks over the top of the vertical strokes, or flat reflected area.
In general, most reflected edges are softer than the edges of whatever they reflect.
I am not really a landscape painter so do not have a big variety of images to show you, so I have selected one of Richard McKinley's lovely pictures, which absolutely does the job! And another below it, by Albert Handell. Do study them with my comments in mind.