At a base level any story can be broken down in three parts; these are the set up, the conflict and the resolution. Of course, this structure can be implemented in many different ways. By this I mean that the narrator can move the story beats around and the point of view can be from anyone's perspective. There are endless possibilities to choose from. But even if shuffled  and mixed the structure is still there. 

The first part of any story is the setup, but it isn't necessarily the part that you will first encounter. This is where we meet the characters, look at the environment, the atmosphere. In short as a reader this is the moment you meet the place, the time and the characters. In a good story the setup will also serve to establish the seeds for the resolution. 

Sometimes as a way of hooking the audience the story starts in the middle of a high stake situation like a fight or a heist. This is in medias res which means in the middle of the action. Taking this approach has positive and negative effects. Let's get through the positives first, a high stake situation can serve to get the audience's attention and curiosity. It can serve to showcase the dynamics between some characters and with that one gets to know the characters themselves. On  the flip side sometimes writers focus more on the action than on the characters, this leads to flare without substance. 

Then we have the conflict. It's something like this: you set up the setting, atmosphere and players; then you give the characters a need and with that an objective to subsidise said need. Once you have that it's time to put roadblocks on your character's journey. 

The conflict can come in many ways. It can be interpersonal, introspective, vague, direct, and so on. There are types of conflict commonly found in stories like these: against others, against oneself, against authority, against the people, against nature, against destiny, and more. The thing that you have to take into account before anything is how are you going to approach your story. Are you going to focus on the plot or on the characters? This is quite important because it can help to choose which kind of conflict is the best for your tale. Alongside that there is what will work better to work off of your characters and make their struggles have a point. This is if you are working with either rounded or dynamic characters. Yes, flat characters will go through ordeals but will not experience any significant changes.

Lastly you have the resolution. This is the closing of the story and the moment where everything is resolved. Well, not exactly. The ending can come with a new conflict, a twist, or even a new start. Sometimes it is neatly tied together, but some other times it is quite the contrary. Whether it is a clean ending or not does not necessarily determine if the resolution is satisfactory or it renders the whole story as a waste of time for the audience. No, the thing that can make or break the last part of any story is how well it works in conjunction with the other parts. If they go well together or not.