Don't draw too slowly, or too fast. Just use a medium pace. One thing's for sure, you don't want to rush it, or it will look bad. Keep practicing, and I'm sure you'll get it!
first, you get the paper in front of you on a hard surface second, you grab your pencil third, you use your pencil to form a picture looking like realistic water on the paper infront of you
that is how....
google: calm stream on image search and copy a pic w/ pencil
oh dude alright if you are doing still water like a lake just fill the whole area a darkish gray and then highlight the shape of small ripples and then smudge and add darkness and more highlights where it looks natural.
and if you wanna draw waves start out filling everything that is not whitewater gray and follow the above steps but it should be highlighted like a solid object w/ ripples. Annndddd with the whitewater.... errr just shade wherethe water is farther away and add droplet and splashy textures everywhere.