How to make reflections in water?

[_sy]

I have seen so many stunning reflective images. Can I get tips on how this works? Is this more to post-production or is this more practical?

Good example of those images are can be found here:
50 Stunning Examples Of Reflective Photography - Smashing Magazine

[pjflan7]

Looking at the pictures, you just have to be there and shoot. There is no technique to it. The reflection is either there or it is not. Obviously, the smoother the surface the better the reflection will be and the 2nd component is light.....cloudy overcast days are generally no good......plain bright sunny day can be great if you are attempting the reflection of objects such as trees, bldgs etc. Often you want clouds and sunrise or sunset if you are attempting reflections off lakes etc. You can even get great images from a water puddle after a rain......the key is keep a sharp eye out for reflective possibilities.

[Sterling]

...unless the subject is a vampire. Then you'll have to add the reflection in post.

[ravncat]

The only real issue with reflections, is that the reflections are darker than the object - so, you generally have to choose

1 - go for exposure of the object
2 - go for exposure of the reflection
3 - try to go for an exposure inbetween

4 - use an ND or grad ND to bring the object exposure down
5 - make things uniform in post, or leave them as is.