We all want to change the world for the better but the truth is, most of us won't. We can, however, support the ones who will and are. There is incredible work being done at the grassroots level by people who never end up on primetime news.
As 80000 Hours explains in more detail, there are really only two ways to positively impact societies - either get your hands dirty or help the ones who are. Although, most of us will not end up with the influence to effect change, many of us will earn enough to spare some for charity. I urge everyone to plegde a fraction of their annual income to charity and revise this fraction as the circumstances improve.
I aim to donate 5% of my annual income every year.
There is, however, a case to be made that charity doesn't help because if it did, government subsidies would have solved poverty by now. As the most famous philanthropist of our times, Bill Gates would have probably solved many other problems by throwing money at the problem. There is some hyperbole there, but you get the idea. This argument has some truth to it. There is a reason why even the best-intentioned billionaires don't just donate all their surplus. The missing piece is sustainability.
This brings me to my only advice on picking your next charity - if you want to make sure that your money gets maximum bang for the buck, donate to institutions that have established sustainability goals. Consider a charity that helps farmers in times of drought by providing their families with food packets and token money for the next season. These efforts would only be worthwhile if the charity is also actively investing part of the money to educate the farmers, say about drought tolerant crops. Further, introducing them to new avenues of livelihood is even better. Every unit of money spent of subsidies is a sustainability opportunity wasted. Without a sustainability outlook, the next disaster will always demand more money. We don't want to be relying on the mercy of a few rich souls.
For the ones that don't have an explicit sustainability goal, make a sensible assessment - is the charity actively investing in sustainability goals? This is not to say that charities focusing on short-term goals are any worse. There will always be times when urgency will take priority over a long-term strategy. I'm just prioritizing my money for the long-term. I hope the government does its job in the short-term with the taxes we pay.
Here are a few that I either regularly donate to or have donated at least once in the past.
Wikipedia: Every single time free-flow of information suffered, societies suffered. Ask the residents of Philadelphia during the Great Influenza of 1918. Ask the people who suffered because of lack of information (or abundance of misinformation) during the COVID-19 pandemic.
Let's Encrypt: Help the world get free SSL certificates. Protect your cyber home(s) from intruders. Don't even go near websites that don't have HTTPS at the least.
Swadesh Foundations: Help them in their mission of rural empowerment by fundamentally reorganizing sources of livelihoods in rural areas.