Training our minds in right direction, we are sometimes confused about what to do in what scenario. We want to know all the steps to follow for all the possibilities that can exist.
But mind is very dynamic (dependent on varied causes/condition which are ever changing), so there are countess possibilities. Therefore, its good to have a attitude of EXPERIMENTATION. We might not know which button to press exactly in all situations, but we learn in the process. We learn what CAUSES lead to which EFFECTS and how changing the causes change the effects. Important is to always keep the observer (mindfulness) intact while doing the experiment.
Like someone asked: "what do I do when I get angry - Observe/Substitute thoughts or Observe Feelings?"
Well, it doesn't matter so much what you apply, as much as if mindfulness is fully intact, you will learn something or the other.
eg: from Thought Substitution: You see cause-effect (how changed thoughts lead to changed result) and thus are not-self.
eg: from Observing Feeling: You notice feelings are impermanence and not-self.
eg: from Observing Body: You learn about how mind and body are interconnected and interdependent.
eg: from analysing the cause of anger: You might see where your attachment lies.
eg: from Observing thoughts and poking your self a question- 'from where did I get this way of thinking?': You might see how your thoughts are conditioned by people, society, culture, media, your habitual patters of thinking you have developed, your assumptions of reality, etc.
...When you get good at this, you can even start playing with your thoughts, by replacing them with thoughts that are more aligned with the reality or are more beneficial and see the effects it has on feelings, body, etc.
So, its not about "knowing beforehand" what to apply to our minds, but working with our mind real-time, tending to what our mind needs at that time. It is similar to how we read the child and see the situation before deciding how to deal with him/her: you are liberal at times while strict when needed; one way of dealing/strategy doesn't suit at all times.
Personally, when my mind goes out of control, I have tries this 5-fold strategy to control my mind. Then when I am in a controllable situation, I gather my mindfulness to observe/investigate anything that I think would be relevant at that situation. If I see thoughts are overpowering, I don't investigate them. The very fact the thoughts are overpowering means that my mind is full of delusion. So if I investigate from that state of mind, I will only condition my thinking further in a wrong direction. So, I observe other objects of mindfulness (as described in satipatthana). In case of anger, changes in body are very apparent and therefore very interesting to observe. So, we can choose the most apparent/interesting thing to observe at that moment which captures our attention. Its easy to maintain our attention on something that is apparent/interesting to us. On the other hand, always deciding beforehand what to observe when this or that emotion arises, would be very constraining/limiting if not forcing/suppressing.