Learn the ropes
This means to learn how to do something. It is a nautical expression dating from the time of sailing ships. Much rope was used on sailing ships for the sails and for many other purposes. A sailor had to learn how the different ropes were used. Today we use this expression when we talk about learning a new job, specifically, becoming accustomed to the job. Example: “I am new at this job so I am still learning the ropes. Maybe in a few weeks I’ll get the hang of it.”
Get the hang of
This means to learn how to handle or do something with skill, through practice or diligence. Once you “get the hang of” something, you are able to do it easily, skillfully, and confidently. If a person has trouble learning how to do something he might say, “I am having trouble getting the hang of it.” A similar expression is get used to which means to become accustomed to. The difference is that get the hang of is used when learning to do something, whereas get used to has a more general usage. For example, “I can’t get used to always having to wear a suit and necktie.” This means, that it feels uncomfortable or awkward probably because for a long time the person never had to wear a suit and necktie. If get the hang of was used in that sentence, “I can’t get the hang of wearing a suit and necktie,” it would mean that the person is having trouble learning how to wear them. That would seem odd and unnatural.
Tell a white lie
This means to tell a seemingly small, insignificant, or harmless lie, often in order not to offend or upset someone. A good example would be a situation where a friend got a new hairstyle or major change in appearance. The friend really likes that change, but you personally think it looks awful. If your friend asks you what you think of the change, and you really think it looks awful, you would not say that, but instead you would probably say that it looks wonderful. That would be an example of telling a white lie. I think this is different from the Japanese expression 噓も方便 because this is what we call an expedient lie. Expedient means “convenient and practical although possibly improper or immoral.” In other words, when we tell an expedient lie we realize that lying is wrong, but telling a lie makes the situation seem to be better.