There are a few things you need to know before starting to crop an artboard in Illustrator. First, make sure that the artboard is properly sized - it should be at least twice the size of your canvas. Second, make sure that the crop area is large enough - it should be at least twice the size of your image. Finally, make sure that you have selected a suitable crop mode - for example, “crop to image.” Once you have these settings in place, start cropping by pressing the “Crop” button on your keyboard.