I would go off and study with meditation masters to hone my ability to disengage from the narrative in my head. This would be of utmost importance given that human psychology is very fragile as is and could break if placed under the kinds of stressors that come with an infinitely long life (e.g. watching everyone you love die, having to constantly relearn almost everything to keep up with scientific progress and new cultural norms, the disillusionment that comes from watching humanity repeat many of the same mistakes over and over again as old generations die off and new generations forget many of the lessons that those generations earned through great sacrifice, ect...).

After that I would probably start to study computer programming and mathematics since becoming good at those two things will serve me well when it comes to finding employment in the future. I would work as a consultant in fields which utilize the knowledge gained from those majors and slowly become more proficient at them. On the side, I would study study finance and investing so that the money I save from work could be put into savings accounts.

After I have made a sizable amount of money, I would change my career path and study law (now that I am good at computer programming I could work on the side while I am in law school). I would get a job as a criminal defense attorney. This would be of vital importance since, as I get older but don't age, I would need to find a way to change my identity and without any criminal connections this would be a difficult thing to pull off. Needless to say, I would also transfer my savings into commodities and keep them at various secure properties which I own.

If I manage to pull all that off, I would have a sizable amount of wealth and also enough extra identities to not end up in some military laboratory. This is when my real work would begin.