You're smart, want to help the world and are willing to work hard. You have no serious ties such as children or a marriage that would prevent you from making serious changes to your life, and you are willing to place others needs ahead of your own hedonistic desires. Given this, what should you do?
Should you aim to get involved personally with causes you feel passionately about? You can have greater control over your contribution if you do this, but can you achieve the most good in this way? Should you operate at a meta-level, such as by trying to convince other people to change their charitable giving, attempting to influence government policy, or by raising awareness of existential risks, or should you try and directly tackle the problems facing the world -- such as by donating money yourself, or by tackling open problems in friendly AI?
Once you've figured out what to do, you still have to find a way to support yourself, and fund any organizations or projects you wish to support. You could work for an existing organization active in the area that you are interested in - bearing in mind that ones contribution will only be the benefit of hiring you rather than the next-best guy. Or you could work in a completely unrelated job, and work part-time on the cause you are interested in; this is a route followed by many open source developers, e.g. the prolific Fabrice Bellard. Alternatively, you could aim to earn as much money as possible, and use this money to fund causes or projects you are interested in; this is the route followed by Jeff Hawkins, who founded Palm, Inc. in order to fund AI and neuroscience research, as well as notable philantropists such as Bill Gates and Warren Buffet.
The problem is a simple one: how should one lead ones life in order to maximize the positive impact it has on others? There is an ample amount of data to draw from, such as charity rankings by GiveWell, salary data and personal experience. If rationality has any real-world benefits, then a discussion amongst rationalists should make it possible for substantially better decisions to be made than would otherwise be the case.
References
Existential Risk Reduction Careers Network
If I were to try to give an ambitious young aspiring rationalist advice, I would say Step 1 is that it's important to be aware of how your mind works.
And since I'm advising you to be aware of how your mind works, I would say the first thing to be aware of is how your mind works when you are focusing on being aware of how your mind works. For instance, when you spend time thinking about how to do things, are you aware of the fact that while you do that you are training yourself to spend time thinking about things?
Depending on your circumstances, it's entirely possible this is a good thing (if you think you don't spend ENOUGH time thinking about things) or a bad thing (if you think you spend TOO MUCH time thinking about things). But either way, being aware that your mind is trainable feels like an exceptionally important fact to be aware of.
I would say Step 2 is that since you want to "maximize the positive impact your life has on others." I would try thinking of that as a procedure and doing it repeatedly to try training it. So today, go and positively impact someone else's life. Then tomorrow, go and positively impact someone ELSE's life, and try to do it a little better than you did the previous day. Or try to cause a positive impact on more people's lives. I do want to note that if you pick the same person every day, you'll may realize you've trained yourself to positively impact THEIR life, and not everyone's. This is fine, and if you do this, good for you, but this isn't what you said you wanted.
Now, at some point, you may find yourself stuck. After all, training for continual improvement is difficult. Maybe you've figured out how to make 100 different people happy at the soup kitchen every day, and you've done that for months and you think "You know, I feel like I could be EVEN MORE useful... but I'm not sure of how." Then that would be a good time to come back for advice. But right now I would recommend seizing the day and grabbing the low hanging positive impact fruit.
As a possible example of low hanging fruit if you need a sample idea for a task that might work for basic positive impact training 101, I recommend giving blood/plasma platelets. It works well as an introductory to helping people for several reasons.
1: It saves lives. 2: There are snacks. 3: Sometimes, there are prizes. 4: It can be added to almost any positive impact program. If for instance, you decide to work on raising millions of dollars for the SIAI... You can generally do that, and give blood/plasma/platelets as well. It just doesn't take much time or effort either, and you can even spend time in the donation center thinking about how you can boost your positive impact higher. In fact, if the center has Wi-fi, you could even be posting in this thread and continuing the discussion.
Thanks, this sounds like good advice -- I've been concentrating a lot on what external actions I should take, and not on what actions I can take to change myself, but those are at least as important.
I've shunned clichéd things like volunteering at a soup kitchen since they seem to me to be quite low impact activities compared to things such as the SIAI, but they might have a larger impact on my self identity than donations to charities, which I've neglected to consider.