Long exposure without filters
If you have a camera capable to operate in manual you can try to give a dreamy look to the photographs choosing the higher number of your aperture to reduce the light and therefore use a long exposure (the camera’s shutter is working more than one second). For example here I used an aperture of F 11 (my lens has an aperture between 2.8 to 16, being 11 the second highest) so the light in the lens was reduced and the time of the shutter was four seconds. Then the clouds more than static are showed in motion like cottons. This technique works better with the less amount of light, so it’s in dawn or dusk. If you cannot control your camera then you could choose the “night” mode.
The downside is that when you use the highest number it appears a phenomena called diffraction that turns a bit imprecise or soft the image, but because that was my intention here is no a problem. When you need motion or movement but at the same time sharpness in a sunny day your best bet is using a quality ND (neutral density) filter to achieve this effect earlier in the day.
In this photograph I wanted to reflect the contrast between the immovable mountains against the travelers little clouds.