Let's start with the high gloss finishes. If your new piano is very shiny, it is almost certainly finished in a thick coat of highly polished polyester. You can find high gloss lacquer finishes, but they are in the minority. Know for sure before you attempt to clean or polish your piano. I will address the polyester type of high gloss finish. Polyester finishes are very hard and thick. They are extremely durable in most ways. A small spill will have no detrimental effect on the finish. Please don't experiment with this at home to see if I'm correct; you don't want liquids near the piano. Trust me that they are water impervious and nonporous. You still do not want liquids getting into the piano. Since so many modern pianos are black (called ebony polish in piano sales speak), they tend to really show dust. I suggest using a very soft dusting tool such as the California Car Duster, which can be purchased at any auto parts store. If you follow the directions for getting it ready for use, it will last almost forever and become your favorite duster for the whole house. Once the piano is dusted, use a polish that is specifically for high gloss piano finishes. There are several good ones out there. DO NOT use common household furniture polishes. EVER!!! Spray the polish onto a high quality microfiber cloth and wipe down the piano. These polishes are almost miraculous in how they deal with finger prints and smudges and will not streak. Most manufacturers have specific finish care instructions on their websites as well. Never spray the polish directly onto the piano itself, or even in the direction of the piano. If the polish were to land on or near the tuning pins or various other parts, you could have a big problem on your hands. Once you've got the hang of it, even a large grand piano can be spiffed up in a couple of minutes.