When it comes to humanely keeping critters out, fences are your first line of defense. Hedges may be more eye-pleasing, but they offer nowhere near the same sort of security.
Dogs can hear and smell critters in your yard very well, and they like to bark and growl at them. This is often enough to scare away the most determined intruder.
Compared to cats, dogs are less likely to maim or kill any critters who have entered your yard, making them the perfect humane, round-the-clock security guard.
Certain plants can deter yard pests, so identify what you’re dealing with and plant accordingly. For example, plants such as basil and chives repel flies and mosquitoes.
Wind chimes may be calming to humans, but the noise they make is startling to many animals. However, note that familiarity with the noise reduces fear over time.
Many critters visit your yard solely to rummage through your trash, so make sure to tightly close and secure the lid of the trash can and avoid unprotected bags of trash.
It's best to keep your trash can in the garage if possible, but if you need to keep it outdoors, move it away from trees, walls, and fences to prevent easy access.