How to do (independent) film-making as a professional career?

[CorleoneArt]

I would love to do film-making as a career, I have always had a passion for it and find it is the only thing that allows me to be creative. I AM NOT TALKING ABOUT HOLLYWOOD BIG BUDGET FILMS! I'm not saying I want to be the next Quentin Tarantino or James Cameron, but I would love to have the same job as the people who make documentary films such as 'Sharkwater' and 'The Dirties'. I am not talking about my films being in cinemas! I am saying, I want to make films that would be entered in indie film festivals like Slamdance Film Festival, etc. Like Rob Stewart (Sharkwater) and Matt Johnson (The Dirties). So what I am talking about is about: How to be an independent film-maker (small group of people) as a career? It is a topic that allows me to be extremely determined and motivated, and for me it's all I want to do. Please be honest in your answers. Thanks.

Also, what qualifications are needed to be a standard film-maker?
I struggle with Science and Maths, but am strong on the English and Literature front. Could this be a problem? Thanks alot.