The deep relaxed embouchure (with the harmonica tilted a bit), is a very good way to learn things such as single notes, and advanced techniques such as bending. It is easier to bend notes with the harmonica tilted a bit. However, once you get really good at bending, you will be able to do it without tilting. But it really helps to tilt the harmonica when you're just starting out.
When doing tongue-block, you block certain holes on the harmonica with your tongue, and leave the holes you want to play unblocked. This is why it is called "tongue block".
Stick to the deep relaxed embouchure at first. Later on, you could decide what suits your playing style. Always keep the harmonica deep in your mouth, and keep the muscles in my mouth relaxed. These two things are important. The tilt angle can change. Over time you will learn to subconsciously shift the tilt angle depending on what song you're playing.
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