Ask HN: Looking for Freelance Work

I am a 16 year old developer, and I find it difficult to obtain a development work. I have a great deal of experience developing iOS applications and developing in Python. I have lesser experience with web design, Java and Javascript. The two main jobs I have managed to obtain are:

• Freelance iOS developer with a startup called dirtcheapapps, developing iOS applications using a rapid development methodology.

• Research programmer at Heriot Watt University, Scotland performing programming work to monitor and control experiments over a summer.

I was also offered the chance to develop the app for roomhopper.co.uk, but unfortunately I declined due to exam pressures earlier this year, which are finished now. Neither of these are long term or consistent work, which is what I would aim to achieve. What should I do to make myself more marketable, and get myself into more jobs like these? Any and all of your advice would be greatly appreciated. Thanks in advance.