The advice I got as I embarked on giving was: Focus on something you're passionate about. There are so many worthy causes, but none that jumped out at me; how could I choose? I was paralyzed by too many options.

I knew that I had a chance to make a difference: I don't need that much money to begin with, and after the Google IPO I had more than I had ever expected. I believe any kids I might have should make their own way in the world, so I didn't need to save money for that. I figured the best use for the money would be to give it away to help causes I was passionate about. All I had to do was find those causes, and it was proving hard.

What I was really passionate about was not a particular cause, but being effective. And while I had a lot of options, I couldn't find any I felt I could be effective at. I kept reading about how hard it was to make a difference, how often attempts to do good could be ineffective or even backfire. There were schools built with donation money that sat vacant due to lack of teachers or books or bathrooms. The food donations to Africa stolen by warlords to support their private militias. The money on cancer research that ended up making a barely noticeable difference in care.

I worked to narrow down the options. My first decision was to focus on the developing world, mostly because the opportunities to do good are so much greater. A million dollars on cancer or diabetes could make hardly any difference; a million dollars on iodine supplements could change millions of lives.

How to narrow things down more? It's a truism to say that all the problems in the developing world are interconnected -- you can't stop the fighting without job security, which you can't do without investment, which you can't get without an honest government, which you can't get without political representation, which you can't get without ... but that didn't make it any easier to focus. I wanted to get to the bottom: one underlying issue where it would be possible to make a difference, and where that difference might 'stick'.

The more I circled round and round, the more attractive education looked. And in particular, I was drawn to education for women. It seemed to me that all sorts of problems in developing countries are made worse by excluding half of the society from participating, economically, politically, and intellectually. A tradition of women's education could start to change that culture, and eventually -- I didn't need the payoff to come quickly -- change the way these countries developed.

So I decided I needed to be systematic about the giving and develop a framework. I wanted to exhaust the money by the time I died and so I gave myself a time frame of 50 years to pace myself. I had financial managers draw up an estimate of how much money I could give away each year, inflation-adjusted, to meet that time frame. (They did those estimates right before the implosion of the stock market last fall, but right now I'm sticking to those figures.) That became my annual giving budget, which allowed me to get a handle on scope, which had been daunting.

Then I divided that budget into three tranches:

• 70%- for Save the World (women's education)
• 20%- for Personal Causes (alma maters, for example)
• 10%- for Friends and Family (projects that people I cared for were personally involved with) 

I found it easier and quicker to decide on the gifts in the smaller groups, in part because the scale was lower and the rationale for giving was based on emotional attachment.

It was harder to move forward on the "Save the World" category. It was harder still to know how to give effectively. I don't know what needs these communities might have, or the best way to fill them. I don't have any connections in the developing world that I could trust as a guide. I don't even know how to tell if money I do give ends up being effective or not.

The solution I've found is to focus giving on groups that do have that knowledge and experience. Of course, then I have to trust the groups to do a good job, but I feel that's a more manageable problem, and well worth the extra level of indirection (I give to a group that gives to a group that does the actual work on the ground).

One group in particular has aligned well with my mission: The Global Fund for Women, which is based in San Francisco. They have a lot of the expertise that I lacked and they are a grant-giving organization that will consider the humblest and simplest requests. By working with them, I feel that I am giving resources to an organization that has an established track record and is in a good position to ramp up. They are large enough to have infrastructure to absorb a large gift, but small groups can also be touched. In addition, I have talked to Room to Read and the Sesame Workshop -- both are large, metrics-based groups, the kind that fill in the gaps I feel I have.

Even with all that, it's hard for me to know how much of a difference I'm making. I feel like for all the progress I've made, I'm still faced with the same issues. Perhaps I'll never fully resolve them. But at least I'm comfortable enough with my direction, that I can start trying to make a difference.