oil painting?

[alphadot]

does anyone have and techniques for painting clouds and ocean waves, its very hard to get the lighting right when the waves are rolling, clouds to is a real mess up, I end up putting too much paint, another question is preparing the canvas i dont know, but when i got my kit i would used this oil before i began putting white and then painting my sky and blending, how do you properly prepare a canvas
i saw some on youtube but some of it was speed painting