We can't stress this piece of advice enough. Grease, sauces and spills are tough enough to clean off a glass-top stove. If you get lazy and leave the cleaning for another day, however, those stains will spell disaster for you. Leaving errant food to sit or reheating burnt-on stains will only complicate your cleaning, and can possibly cost you a lot of money.
All food should be removed as soon as the stove is cool, but some foods are worse than others. Sugary or sticky spills, such as syrup or jelly, can actually make its way into the glass, causing pitting and cracking. Foods that get really stubborn when dried out, such as tomato sauce, grease or even water from an boiling pot require more pressure from you when rubbing out stains. This can also cause the glass to crack. A shattered glass top is usually not covered under a normal "wear and tear" warranty, so you would be responsible for replacing it. However, if you're vigilant about keeping your glass-top stove clean, you'll be rewarded with a stain-free, polished appliance that will bring you years of use and many memorable meals!