Eating less animal-based food and going for the less greenhouse-gases emitting vehicles (walk>bike>train> bus>e-cars>cars>planes) are the two biggest impact fields for the global warming problem, if i'm not mistaken.

For other problems such as plastic pollution, chemicals, etc., i think a good option is to minimize the waste you "generate" : avoiding plastic bags or containers, as well as aluminium/metal ones, glass is better especially if you reuse it, cardboard and paper are a bit better too though far from perfect.

Maybe some local farms or shops produce things with environment in mind (or at least more than others), like organic farming, ethic woodcutting, etc. It's never perfect, some are mainly greenwashing, others really try their best, most are in-between, but most of the time it's a better option than classic ones.