On reading Part 1, one gets the impression that the methods advised are in some order of difficulty; but that it not true. Every man has a different belief, nature and belong to different sections of the society, hence a method may appear easier to one and difficult to another. Nor do they lead to different ends; they all have the same end - achieving God.
The first method is apt for a man who has feels the love for God straight from his heart; one who has an ardent desire to know the essence of God and would love to spend his whole life looking for the ultimate truth. This is what is natural to them.
Then there are men who have faith in God and want to engage their mind in the thoughts of the Supreme one. Such men should practice the said exercises.
Another type of men is who like to pray regularly, make donations and perform rituals. The third method is for these people. This is what is inherent in their nature.
The last method is for men who believe that God does not take any particular form and they believe in doing something for the welfare of one and all.
As we can see one must do what is natural to them; but do it from the heart, with all their faith and completely believe in what they're doing. Now that I've written it, I can see that this applies to our everyday life also. If we do some work, with complete faith and whole-heartedly we will always succeed in it. Once again I can see how Gita gives you principles for everyday life.