These are generally the easiest parts of the bathroom vanity to care for, but they also see the most use and abuse over the years. Hardware is generally easy to clean with baking soda or apple cider vinegar but be careful not to use something that will cause corrosion or other damage depending on the finish of the hardware.
And for clarification, the hardware we’re referring to is the faucet and tap(s), as well as the sink drain, which is usually also made of stainless steel. Taking care of these elements isn’t difficult. Be careful not to scratch chrome and other metal finishes when cleaning because that can ruin the aesthetic even if it doesn’t cause any real damage.
The care for your sink and counter will vary depending on a few factors. Some vanities have a sink and counter that is a single piece and sits on a vanity base. Others include a separate sink and counter, in which case the sink could be inset, set on the counter, or even a bowl-style countertop sink. Usually, simple cleaners without abrasives or harsh chemicals will be effective while preventing potential damage from the cleaning process, which will help your vanity last longer.
Always start with a soft sponge or towel and only use an abrasive surface if necessary (and if safe to do so), on a soft, porous surface, you may have to be careful about abrasions and stain removal because of potential damage. If you’re not sure, look up how to care for the material that your bathroom sink and counter are made of.