Hello Budrub! When you paint your skies, do you have your paper flat or at an angle?
The things to consider are;
Angle of Paper
For the paint to flow, there needs to be a "fall" on the paper, so that the colours you apply will try to find their way down the paper; you can also turn the paper around so that you move the paint flow in different directions to achieve various effects
Strength / Thickness of the paint
Have a scrap piece of watercolour paper to test the strength of your paint, and either weaken or strengthen it to achieve the intensity you want
Dampness of Paper
Stretch the paper by wetting it thoroughly, mopping it with a clean cloth to take off the excess water then tape it down onto a suitable board. If its dried off when you want to start the painting, wet the sky area with clean water - depending upon the paper size, I usually use a 1" Flat, or a No.16 Round - then paint a couple of swathes of your colour onto the wet paper, leaving some white spaces if the sky is cloudy, then control how you want the colour to run by turning the paper around. Try also dropping touches of, say, weak Paynes Grey or weak Burnt Sienna into the (still wet) sky to introduce a little English weather!
You will get there in the end if you keep practicing!
Lets know if it helps, or not!