Use a water butt to collect rainfall. Use this on the garden rather than tap water;
it's better for the plants and better for your wallet.
Start composting. A great way of turning food waste into something useful rather
than sending it to landfill. Compost bins come in all shapes and sizes to fit any space, and are
readily available from garden centres.
Grow your own vegetables. It will take a bit of time and effort, but the veg will
taste fantastic and the associated food miles will be zero. For the less confident, garden centres and
places like B&Q sell all-in-one potato growing pots that can go on a patio, and mushroom boxes that can
be kept in a garage.
Grow trees and wild flowers. Native trees typical of your locality will use up carbon
dioxide when growing and encourage wildlife into your garden.
Don't use patio heaters. We are managing to warm the planet quite well enough
already without any help from these monstrosities.