I am a freelance developer and I basically develop ERP, graphics software, components, web and other such things. I always thought about an open source development of the software that I basically work upon and I am sure one can easily make his/her project open source.
I am also planning to make my applications open source but the problem is that after making everything open sourced how will I get finance to continue the work and sustain my life and future? I know I can ask about the donations of my work from the peoples who are using my applications.
There are many big communities and companies who are into open source market. From where do they get finance and continue their work?
Somewhat two different questions - 1) making something open source & 2) getting paid.
Making something open source is easy, select an appropriate licensing model, update code & put it on github, google, sourceforge or wherever you like.
How you get paid for such effort is a challenge - if there were a simple way, I'm certain many people here would have already made millions and be retired by now. Here's another question on the board that gives some ideas - Making money out of a free and open-source application In general, depending on the specific software and demand, customers may find your software useful and hire you to customize it for their particular needs. Others may look at your software as a validation of your skills and work with you on an entirely different project.
Best of luck.