1. Raise the carriage of your lawnmower. Like: All the way. Most people cut their grass much too short. Taller grass provides better coverage and can reduce the need for watering by shading the soil and slowing evaporation.

2. What's the most eco-friendly lawn mower? One of these bad boys: https://www.popularmechanics.com/home/lawn-garden/g40061434/best-reel-mowers/

3. Bald patches? That's your yard telling you that grass doesn't belong there. Just till that plot and plant something else — preferably something that grows locally. Particularly if you're in a hot, dry region (as more and more of us will find ourselves, going forward), the practice of xeriscaping is your friend: https://en.wikipedia.org/wiki/Xeriscaping

4. Plant other stuff anyway. Local ecosystems thrive on plant diversity. People (especially Americans) have this warped, neo-Victorian ideal of a monoculture yard containing nothing but neatly trimmed Bermuda grass, and that's just not healthy.