Hydration of your whole body by drinking water is best for keeping your vocal tract hydrated enough. But if you need a little extra, especially in winter when the weather and the indoor heating systems can dry everything out, steaming for a few minutes can be really helpful. And it's really easy.
The easiest thing to do is to boil a medium sized pot of water, turn off the heat, and after a few minutes, but while it is still steaming, drape a towel over your head and shoulders, then lean over the pot to breath in the steam. You might consider using distilled water if you are concerned about impurities that might be present in tap water. Spend a few minutes over the steam, breathing deeply but normally, and let the steam droplets cover your vocal tract. I like to alternate between breathing through my nose and through my mouth so that I can also get some of that steam goodness in my nasal passages.
If you don't have time to stand over a stove, or you don't want to end up looking like a sweaty mess (because that's absolutely gonna happen), you can get a quick hit of steam from a mug of steaming hot water before you drop in a tea bag or while it's steeping.
If you want to get super fancy, or need to travel and aren't sure about the accommodations, there are steaming accessories you can get for yourself. I have colleagues that swear by them. I personally don't care for them because I'm just a bit claustrophobic, and having something on my face is uncomfortable. So I do it the old school way, and it works well.
Try it today! Do you notice anything different after you've spent a few minutes steaming? Any other tips or tricks? Share them with us!