You can do a couple of things to make your SketchUp renderings look more realistic. First, make sure you're using the right SketchUp settings. Go into the 'Preferences menu and adjust the settings for shadows, lighting, and colors. This will make a big difference in how your final rendering looks. Second, pay attention to the details. Make sure that objects in your scene are correctly scaled and that they cast accurate shadows. Third, add some finishing touches like trees, people, or animals to really bring your scene to life. By following these tips, you'll be well on your way to creating realistic SketchUp renderings that will impress your clients and colleagues.