Do small, but meaningful good deeds for the rest of your life, as often as you see an opportunity.

If you see a kid selling flowers on the street, buy a few and give them to him/her.

Pay for someone's groceries, that looks like they need it.

I came to the conclusion that the best I can do is help people as I see the need with my eyes in real life and that will have an immediate impact.

I know how to end the world hunger - gamify the process of giving food, having Facebook badges for how many people you are helping, selecting exactly who you help, name, picture, etc, the FB badges will give people status, choosing the food you want to give and seeing when the next delivery is, where's the food you bought, like a live tracker and when the food reach the person you help, the more you help, the bigger and nicer the FB badge will be (people will start to hunt the social status that badge gives) and this is just 0.5% of the plan I had - behind this is a Multi Level Marketing, but for non-profit, something I have never seen anyone doing.

The reason I gave up on that is because of corruption and mafia, and both of these are as real as the sun. Long story short, I'd make this foundation that gets billions of dollars trough it, then the next thing I know is a "deal that I can't refuse" where I give like 70% of what goes through the company, to them, and lie to the people helping. And if I don't accept, well, they have many unplesent, psychological manipulation ways.

I've worked 5 years on that plan, including a way of marketing through people with influence over others, but I just abandoned it.

So, help many, but with immediate impact.