Absolutely nothing other than voting. Any individual "reducing their plastic use" is just a drop in the ocean. The only meaningful change is through legislation or some economic situation. The only positive outcome of reducing your own plastic use is that warm and fuzzy feeling that you get from believing that you are doing something good.
However, I do not want to discredit that warm and fuzzy feeling. It brings people joy, and I think that is great.
I just want to comment to push this comment higher. On a PC, the answer is usually Firefox.