Regarding the steps in painting: I have a definite goal for each painting of this scale. This is not like an 8X10. Here I plan well ahead to display what I feel about a scene. If some elements in the painting are missing, obviously the picture remains incomplete. Without those trees there is nothing through which I can connect with the sky spiritually. Even an angle change in that swamp area leading towards the trees will make it look incomplete or distorted to me. So, there are no various paitings here. It is just one. I did make changes in some of my previous paintings but they were the results of poor planning.
Regarding composition: this is very subjective. I generally follow golden mean. Everything fits there. But here if I follow golden mean, the whole thing will change. Position and the size of the trees have to be dominant. Can't be smaller or bigger than what they are. Sky is a very powerful. The painting will be without drama with less sky. If I show more sky then it will be too much power. I won't be able to fullfil my emotions properly if there is a slight change in this composition. This is an agricultural flat land. There is no variation in this for miles. In a way the irregular vertical elements break the monotony and create greatness in ordinary. There are thousands of examples in historic paintings with equal split. I wouldn't try this in a mountain scene though. For intimate corners I will follow Constable's diagonal split. I have been planning to buy Carlson's book, added on my amazon wish list six months ago. Will buy that pretty soon. But I feel for composition it is important to find out what a scene demands and then work accordingly.
@anwesha these are all leanings. We progress through faults. I suggest you start painting from life for landscapes; start in your garden or an area where you can paint without disturbance and study how light affects the values of things! After three paintings you'll see the difference. You'll need theory though to produce good paintings