Well, one environmental habit I've got into over the last couple of years is strictly separating all our kitchen waste and composting raw food scraps in a small bin on our balcony. Essentially, it means none of our vegetable peelings, coffee grounds, or eggshells end up in the general rubbish. Instead, we let them break down naturally into nutrient-rich soil.
I actually started doing this back when I moved into my current flat. I noticed just how quickly our main rubbish bin was filling up, and to be honest, it was quite alarming seeing how much organic matter we were simply throwing away. I bought a compact, airtight composting container and made a conscious effort to keep it next to the sink so it became second nature to scrape scraps into it rather than the main bin.
To start with, it was a bit fiddly, mainly because you have to be careful about what you put in, no cooked oils or dairy, for instance, otherwise it starts to smell foul. But once my flatmate and I got the hang of the routine, it became surprisingly low-effort. It only takes a minute or two each day to manage.
In terms of effectiveness, I'd say it has made a massive difference to our environmental footprint. We've managed to cut down our general rubbish collection by at least half, which means far fewer plastic bin bags going to landfill. On top of that, we use the finished compost for our potted herbs and houseplants, so it creates a neat, closed-loop cycle right at home. It is a small adjustment, but it definitely feels rewarding to see tangible results from everyday choices.