5 Words: Fire. Lava. Death. Mobs. Pain. (jk its not THAT bad)
just don't sleep in Nether. Or fall into lava. or hit a zombie pigman or piglins. stay away from hoglins, ghasts and blaze have projectile weapons, wither skeletons poison u, water does not work, magma cubes are way more dangerous than everyone says, piglins with black outfits are Brutes, don't steal from bastions, get fire protection armor but at least one piece has to be gold. Shields are reccomended (personally), and try to make a couple of emergency hideouts, if u r on low health.
other than that, it's not THAT bad (hehe)