What makes a good short film?

To produce a product that is going to be popular with an audience, I need to know how to make a good short film so that people will actually watch it and be interested to pass it on to other people.

Short Films
When looking at other short films, I found that there were certain codes and conventions to shorts. As a group we will have to decide which codes and conventions to go with and which to go against with justification.
I found that in most shorts that there was one main event focusing on one main character. I didn't really get to know any of the characters and the stories are usually a emotional journey of one's life. As the stories are fast paced there is usually an immediate build up or consequences to an event. Some of the stories were based around a familiar event such as Christmas, the first day at school, a wedding which gives a fixed time frame adding to the realism.
Short films are usually less than 30 minutes in length.

Our Short Film - The Character and the problem
We answered several questions that made sure our story was going to be strong enough to make into a film.
Who is the main character?
Lily, who is the younger sister of Leon. The camera will follow her life, her emotions and reactions. She is 12 years old and lives with her brother and mother. Her Dad has nothing to do with either Leon or her.
What is their problem?
The problem is that she is worried for her brother, Leon who seems to be getting himself into trouble, by coming in late, getting more aggresive and angry and pushing his family away. Lily will hear various things happening such as arguements between Leon and his mother, and between Leon and a friend. Lily keeps looking at Leon for comfort and to let her know that everything is okay, but doesn't get a positive response back.
How will the audience recognise the problem?
Lily will have hardly any speech or none at all to show that she is thinking about her brother and what is going on. She will be a shy character that Leon "shoves" around. There will also be arguements between friends and family so this will also show the audience the deterioration of Leon.
Are the stakes high enough?
I believe so. There are films such as Kidulthood and This Is England which show the response of gang violence from the actual person involved perspective. We are going to turn this idea around so that it shows how the family are affected as there have been families out there who have seen their siblings/son's/daughters one day and they are gone the next. It's a delicate matter for the families involved and we want to represent this through a film. We don't want to conclude it though, as we will let the audience wonder what happens to Leon. This may mean that the audience remembers our film.
Are we telling the story from the best point of view?
We are telling the story from Lily's point of view, the sister to Leon, who is getting himself into trouble. Films have been made before that are from the point of view to the person in trouble so we want to create a short that is from a younger siblings point of view. The younger siblings are normally the one's that get left behind, the one that gets forgotten when the other sibling has all the attention.
What does our story mean?
It makes families aware of how siblings feel in difficult situations such as seeing a brother get himself into trouble and how the trouble gets back to the family home. It also makes teenagers aware that what they do has an effect on their younger siblings, after all we all look up to people who are older than us to know what to do and how to do it.