Everyone needs a metronome. Here are four of my favorites. I own the Yamaha because it can be set to silent to use just the flashing light.
The wrong humidity level is bad for you, your plants, your instruments, your wood furniture, your pets, even your electronics. The recommended humidity range is between 45-55%. It’s a good idea to calibrate your hygrometers at least yearly.
If you’re looking for classical music, and you’re just beginning to explore the composers, a really inexpensive introduction is the Big Box sets. Much more than “Greatest Hits,” these are, at a minimum, competent performances that will help you gain familiarity with the works and at 99 cents per album, the price is unbeatable. I’ve seen these big box sets comprise more than 150 tracks.