If you want to save the world we know, the things that help most are:

1. Have one child at most and encourage this policy at all times. Birth control, condoms, abstaining whatever the simple economics doesn’t care. This is by far the best thing you can do. Even if 3 vegan kids consume less resources than 1 “average” kid. In the next generation, the 9 ecowarriers to the half kid of the single child model won’t.
2. Eat locally made produce indeed the more local the better.
3. Don’t travel by plane. Cheaply broadening your mind is killing the planet. Recovering this carbon footprint is very difficult. Plus even if you do recover it your supporting an industry that certainly does not.
4. Do not buy organic food it’s less efficient land usage. If it went mainstream it would result in bigger farms and less “natural” land. Cows are very inefficient fertilizer synthesis machines cleaner chemical plants are what is needed. (Possibly you could extend this argument to GM but the results aren’t clear yet).
4. Support nuclear as a quick fix until solar gets there. Yes, yes I know this is controversial but kwh/kg it’s by a mile the most efficient standard solution. Plus and very crucially the waste is dangerous but concentrated and thus localized. (The biodiversity increase around the reactor area at chernobyl since the accident shows people are much worse for nature than radiation).

Or you could, live as you pretty much were before. Driving your 4 kids to school with their lunch boxes full of non nestle, organic, non GM foreign produce toting sound bites about deforestation and blaming America (or companies if your American) whilst praying for supernatural intervention.