Wetter is better
Every living organism requires water to some extent, so whether it’s a pond, puddle or muddy patch, providing wetness will hugely benefit a wide range of species. If you have a small garden, you could drop an old kitchen bowl in the ground – pop some decent sized stones in to allow animals to climb out (and give plants somewhere to establish) and hey presto a pond.
Feed the young as well as the adult
We all know that nectar-rich flowers are great for butterflies; however, all invertebrates have at least one juvenile phase that requires its own food source. Many species of caterpillar are quite specific about what they will eat, but providing an undisturbed patch of nettle, bramble or birds-foot trefoil, each of which can support numerous species, can be very helpful in enabling butterflies and moths to thrive. Butterfly[1]conservation.org is a great resource if you have a particular species you’d like to support.
Dead is alive
Many invertebrates and fungi live on dead and dying species. Rather than rigorously clearing away dead or dying leaves, branches, trees etc, setting aside an area for decaying vegetation – especially dead wood – can support a wide variety of species.
Connect, connect, connect
Linear habitats are great for helping things get around. If you can plant a hedge rather than have a solid picket fence for a boundary, it will not only provide lots of homes and food for animals but also provide a sheltered highway to get from one place to another. Road verges and field boundaries are also very important for this reason.
Drop the bottle
If you can avoid using chemicals on your land, please do. Most chemical pesticides kill a much wider range of species than they need to for the intended purpose, so applying them may have unintended consequences. Natural management, through native predators, manual methods, adaptive planting or a certain degree of tolerance, are almost always better for biodiversity in the long run.