Something simple I had done was that I invested in USB powered grow lights for my indoor plants, as the apartment I had a few years ago was in the worst position for getting light. If you have a good window, feel free to set up something small for now, some herbs or even flowers for just adding a bit of nature into your life. People mentioned the different options for composting, which I agree with as well. The idea of setting up portable solar panels if you can afford them, for little stuff is a good idea too. It is really up to you, what you feel you can do and start with! A big part also is that solarpunk isn't just at home, it also is in the community.