A good first place to start when it comes to trying to find a job that will assist the greater good would be a non profit that advocates for a cause that you have a passion for. The saying of that if it’s your dream it wont be a job is very true, and if you start where you have a passion it is definitely a head start. Within the non profit of your choice you can pick and choose from the jobs that you specialize in.
Another good option would be becoming a corporate philanthropist and working to create a better environment from within your company. You would be able to again choose a company that you connect with and from there you will again be able to work for the cause of giving back to the community and doing good!
The last option, but also the most risky, is that you could always start your own company or non profit that advocates for whatever you personally believe in or are passionate about, whether it be a company that helps make the planet more green or helps those in disasters, starting a company that you feel a connection with in helping the greater good will definitely be rewarding.