This is kind of specific to you. What is important to you? Saving the earth, environment, animals, helping humans, self-growth, making more money, living happier, etc.?
Pick something that matters to you or else you won’t likely have the drive to stick with it and make it happen.
If you don’t know yet, then take the time to slow down, and figure it out so that you don’t spend a year “trying” everything and getting nowhere.
I would rather take three months to figure out what I want to do and where I want to end up at the end of the year and spend 9 months taking laser-focused action to get there (even if I don’t quite reach that happy end result in 9 months) versus spending 12 months of dabbling, lacking direction, doing a ton of work and thinking I am getting somewhere only to find out at the end of the year I accomplished absolutely nothing.
I am sure all of us answering on Quora can give you a list of potentials, good for ideas but you still would have to figure out what resonates for you.
So again, I would spend the time to figure out a resolution that would be meaningful to you, especially if you want to actually keep it.