After inserting a GIF, you can align it perfectly in the center of a slide by selecting the GIF and then going to the 'Format' tab. Click on 'Align' in the Arrange group, and then select 'Align Center' and 'Align Middle' sequentially. This ensures the GIF is centered both horizontally and vertically on the slide. If 'Align' is grayed out, make sure you've clicked on your GIF to select it, and that the 'Snap objects to grid' option under PowerPoint options is enabled.