First things first identify the main place the sound is coming in or out of, whether it’s a door or a window or simply just a thin wall. That area will need the most proofing, so what you want to do is take a blanket and stuff it in the cracks or cover the door with it, you can do this with paper too With windows you want to just cover it completely. The material of the blankets will absorb some of the sound reflected off them. It help out side sounds seem less harsh and more muffled. With walls you’d want to put a blanket or foam on it using tape

This is good for if you’re a light sleeper and wake easily from outside sounds or if you have sensory issues and need a quiet place, also works if you’re trying to study and you get easily distracted

You can! That works too. The thicker the blanket the less the noise

That works too but not everyone has a closet

That’s perfect! Do whatever works for you 😁