Any suggestions?
It could be good to focus on one axis: personal career value, or affecting the world and helping people. They seem to rarely line up.
If you want career value, try Node or C#. Both will put you in a position to get a high salary job for a long time to come. C++ won't unless you're willing to move around the world.
If you want to do something useful for many people, one way is to find an open source project you like and start trying to contribute. If your contributions are rejected, move on and try a new one.
If you want to start something new, focus on what's fun for you and pursue that. If you go into it feeling like a bunch of people are counting on whatever you're making, you'll risk burning yourself out. That's just my experience though.
Good luck.
I would say your best bet is to focus on skill. If you can dive into a large C++ codebase and solve a crash, you're skilled, and people will find your contributions helpful once you're there. So that's really not such a high bar to aim for.
In terms of experience, this tends not to matter too much. Use a talent agency to place you in the field. They will take a chunk of whatever value you would have otherwise pocketed in salary. But it's a way of getting in to the industry that I know from experience works. It's much more effective than trying to send resumes or cold call managers, which is why it might have seemed like "experience" is a necessary requirement.
Experience is just a proxy for skill, so if you have skill, you're fine. A portfolio is helpful, and I'm sorry to say I can't think of specific projects that you might like to work on. But I know that if you can optimize a trading company's firewall-to-firewall time, you're highly valuable to them.
The financial sector is what I'm thinking about, but I've always though thought that it is hard to find a job in this sector without a solid experience. So the idea about a talent agency seems to be helpful.
BTW I'd like to ask about a relocation. Is it right that it is easier to find a position that offers relocation (I mean H1B visa) in some financial institution rather than in an internet company?
That would be an interesting Ask HN question. I think a lot of people would like to know.
One reason the financial sector might be easier for H1B visas is that they sometimes treat their employees very poorly. But I know of good companies as well, so it depends entirely on the company.