Add Water
Not every garden has, or wants a pond but a little goes a long way.
A source of fresh, clean water will encourage birds and beasties alike to stop in your garden.
It doesn't need to be elaborate - a basin, bucket, tub or a bowl is a brilliant start.
Remember to keep it clean and fresh, make sure it's no deeper than 3" and put some stones in the dish to help them any visitor get out.