Something that moral philosophers have been striving to define for centuries is a universal morality. A guideline for right and wrong that can be applied in very situation, without exceptions. In doing so, moral philosophers have actually pointed out just how subjective morality is. How the idea of a universal morality is impossible.
You pretty much have three types of moral theories;
A deontological theory focuses on the motives of an action. So if you intended to kill someone but failed - that action is morally wrong, even though you did not complete your intention. On the other hand, teleological theory focuses on the outcome of an action. So if you meant to help someone across the street but accidentally pushed them into traffic resulting in their death - that action is morally wrong. If you apply each type of theory to the other example, you get a different answer of whether the action was morally right or wrong.
In our legal system, we apply both these types of moral philosophy. For example, punishment for attempted murder is based on deontological theories, whereas manslaughter is based on teleological theories. Now, with two categories literally saying that the opposite thing is moral to what the other suggests - how can anyone categorically, absolutely say that an action is right or wrong?
You then have Aristotelian ethics, which focuses on the individual, on our intuition and what our "gut-feeling" tells us. This type of moral philosophy is the one most of us can agree with and relate to. However, if we apply this line of thinking - we're assuming that everyone's intuitions are the same. And while this can be true in some cases, in the vast majority of situations there will be someone who disagrees. What then? Is it what the majority say goes? Do we disregard the underdog?
So, if there is no universal morality, then how can we decide what we should and shouldn't do? Well, I believe that morality is individual. That what I think is right you may not think is right. For example, I believe that every animal is equal. A human to a fly. This is an unpopular opinion and most people would say killing a person is a lot worse than killing a fly. Don't you? This disagreement right here proves my point. What I think is wrong, you may not. And that's okay. It's natural for us to put ourselves in someone else's shoes - "would I have done that in that situation?". This role-reversal automatically makes us judge that person's actions based on what we think we would do and against our own individual morals. But really, who are you to judge?
Morals are the guidelines by which we live our lives. We each have our own moral compass telling us which way is North. And although this may be the case, universal morality - a morality that we can all agree and adhere to - well that morality is made up.