Lets say you just got the game, your new to this and don't really know what to start off doing. You're in luck! I have some tips for you today.
Let's get started
When you first make a world, the first thing you want to do is gather wood. With wood not only can you make tools, but it can also be used for shelter before night hits. No one wants to be killed by those pesky mobs at night so they?

Make sure you get food as well, in normal mode and over your hunger tends to drain pretty fast, and with that leads to slowness eventually. After you have lost all your hunger you will die. The best food is either steak or porkchop. Make sure to cook it!

When swimming in water, it's best to look out for drowns. They are mobs that are like zombies, except they can swim and some even have tridents.

When mining, don't dig straight down. Digging straight down can sometimes lead to lava, and if you fall into that you're probably doomed.

Want to go to the nether? You need to build a portal! You also need to make sure you at least have iron armor before you go. It can be dangerous with all those mobs. Make sure not to hit a piglin, if you do that, well you're dead.
Here's what a nether portal looks like for reference: