I think you ask good question and you hit on a profoundly human need to help each other. Since I have left the JWs, I work with a number of charities for health, justice, and a better planet. One of the best times I had was serving food in the local shelter during Christmas. We are wired to do good beyond what any religion and scripture prescribes.
However, if you are looking to help and don't know where to start, act locally. There are lots of people around your vicinity that need food and services. In addition, the so called "worldly people" have a better handle on what things to contribute to than most JWs. Asking the people around you is a good place to start.
One thing I realized when you leave and want to help is that the problems in the world can seem overwhelming and makes it hard to know where to start. Start locally, simply, and do a small thing every day.
On a side note, one of the things I have been working on in my spare time (for fun) is to develop a set of heuristics that will help evaluate what people care about (via a simple guided questionnaire) and match them to a charity. I think, people want to help but are often overwhelmed. Also, I have also changed my investments so that I support companies that improve the world and/or have strong socially conscious policies, even if it means a loss to my bottom line. Act locally. Think globally.