Aside from the paint itself, minimising environmental damage during the process of painting involves considering things like the type of painter's tape you're using (I have yet to find a completely home-compostable masking tape!) and the drop sheets you'll use to protect things you do not intend to paint.
We used old bed sheets, towels, and newspapers to line our front deck and the surrounding walls. The newspaper was composted and the bed sheets and towels were washed and will be used again.
Lastly, the environmental impact of your paint job will be determined by what you do with your leftover paint. And what about the tin?
I used our leftover paint for small DIY projects and will continue to use it up as my urges to paint my home bright orange intensify. When the tin is empty, I will turn it into something handy, like a vase or a plant pot.
It's great to see places like The Natural Paint Co. and Resene implement return systems. Leftover paint can be sent back to these companies, to be passed on to community groups or recycled responsibly.
Whatever you do, don’t dump paint (especially the toxic stuff) in a rubbish bin.