In this last step, we will use the brush tool to make our shadow perfect. First, go to the toolbar at the left and find an icon with a brush on it. Click on the icon, and a drop-down menu will appear. From there, select the Brush Tool.
After selecting the tool, set the opacity level around 50-60% before starting using it. Now change the background color to black and fix the brush size according to your requirements.
Now drag the brush tool over the shadow to make it smooth and realistic looking. If you overdo it, change the background color to white and paint it over that area with the brush tool again to retrieve it.
By repeating this back and forth process, work until you get your desired amount of drop shadow.