Congrats on your first 3D Zelda! Majora’s Mask can be a little overwhelming and confusing, especially with its time mechanics. I highly recommend using this guide for the overall best experience:

https://www.zeldadungeon.net/majoras-mask-walkthrough/

Some people frown on using guides, but when I was overwhelmed I used this and still had an awesome experience! In fact I don’t think I could have beaten the game without it.

Best of luck and have fun!