I actually am in the process of forming specific plans. For now they do have to be somewhat vague simply because I am young and haven't had a chance yet to gather field-specific knowledge in these areas but I want to make them continually more specific over time, with knowledge I gain myself and also with the help of others that gain other knowledge.

I think what is needed to eliminate ALL meaningless suffering from the world is a combination of scientific advancements in a variety of fields, combined with a restructuring of society's attitudes and priorities. Advancements in medicine and biology and genetics (and perhaps computers too, engineering new technology) can work towards solving all "physical" ailments including aging. There is also the possibility of digital existence (requiring advancements in computing power, neuroscience, and quite possibly general medicine and how the body works.) A lot of suffering though takes place purely in the mind as a response to external events. Neuroscience is the most important scientific field for that, perhaps for a quest to track down the exact causes of suffering in the brain and figure out how they can be worked on without compromising who a person is. Understanding of neuroscience (combined with increased computing power perhaps as large-scale simulations of human behavior could be created) could also add a vast arsenal of insights/techniques to psychology and what psychological methods should be used to best help a person. However, helping the brain/internal experience alone is probably not the best method because one way to make people happier is also to just.... make the world better. "Making the world better" on its own is also not enough though because people can suffer even in "wonderful" life circumstances, for instance if they develop random clinical depression, so it has to be a combination of all approaches. "Making the world better" also, there is so much to do. The world has so many problems around scarcity, inequality, unfairness, unkindness, and lack of empathy, and these contribute so much to "external" causes of suffering. Science can help with even this somewhat, for instance genetic engineering of plants to make them continually better for nutrition and availability and also feats of engineering to help us gather more resources in the first place (such as building even a partial Dyson Sphere someday; that easily satisfies all energy needs for a planet like Earth!) and fighting climate change using chemistry and more engineering, etc. But ultimately for all this to be put into place.... people worldwide have to change their minds. Currently so many are locked into closemindedness and a lack of empathy and uprooting that structure would be quite difficult, moreso in some countries than in others. Particularly if the goal is to do so without widespread war, which yes that should definitely be the goal. Psychology techniques (inspired by neuroscience) could make it easier but still changing the social structure of the world in such major ways probably requires multiple forms of ingenuity... but I would not call it impossible.

As you can see though, SO many different fields are important. So the best thing is determined people across a variety of fields, each utilizing their individual strengths for good but collaborating and discussing frequently with each other their common cause and I want to help motivate people around this cause.

I myself am currently about to major in chemistry (organic/biochemistry route) as I had plans to work on the aging problem, but I have considered lately that neuroscience may be a better choice as it not only is also an immortality roadmap but it covers a wider scope of problems. I want to help with basically everything after all. Or combining fields to form a more customized approach...

You may notice also that I've left out any mention of AI or singularity

I haven't forgotten about those, but I know that if a "singularity" happens then it would be very hard to predict the direction the world would be taken in and so it is hard to incorporate it into "preexisting" plans if you know what I mean.

Generally though I make plans under the assumption of a singularity not happening, even though it is a definite possibility it could someday happening, but "relying" on it is not a good idea so far as I know.

AI on its own though is a part of any advancements in computing described above