While all advice on gardening for wildlife is useful, you could follow the simplistic “Seaspiracy” conclusion of just "don’t eat fish" to say just "don’t tidy the garden".
However, this would be missing the point on two fronts: People enjoy gardening and it's that enjoyment we want to nurture and encourage to create the diversity of habitats which makes gardens so important for wildlife.
So yes plant for bee friendly flowers and mow the lawn less but if you want to get more scientific, more specific, for individual species, you have to dig a little deeper. Here are two observations for you:
Long tailed tits love our fat balls on the bird table but how do we encourage them to nest in a safe environment? They like spikey, thorny dense bushes for cover. The nest shown is in a red berberis which I have been tightly pruning for 3 years to make a suitable habitat and hey bingo it worked! I have also ordered 3 gorse bushes to plant alongside so I create a perfect long tailed tit nesting ecosystem.
Our mistle thrushes which nest every year (we are currently blessed with three nests) always follow the same pattern. They choose a mature larch tree with a large horizontal branch, at least 4 meters from the ground, preferably with some cover over the top of their nest which comes into needles, protecting the chicks, just as they grow too large for their parents to brood. This is important as they can be fairly exposed nesting as early as they do. Then once the chicks fledge they immediately seek out nearby mature birch trees where they sit high up, waiting for their parents to continue feeding them. They are very successful and act as natural cat, squirrel, magpie and crow deterrent with aggressive lunges at anything approaching their territories. Now we cannot all conjure up or have the space for mature larches and birch trees but we can be more specific in how we attract certain species.