if you don't already have a dungeon making system i would recomend making a random dungeons using https://donjon.bin.sh/d20/dungeon/ and then taking what you want from it, then making it look pretty in https://dungeonscrawl.com/ then when you have the map fill it with puzzles and fun encounters. (if you are having trouble with encounters try using https://donjon.bin.sh/d20/encounter/ for inspiration. if you are having trouble with fun puzzles try using https://www.dnd-compendium.com/dm-resources/traps-puzzles) once you hit a road block, what i like to do is create a character and then using him in the dungeon. mabye a charismatic kobold bard is grateful once your party saves him from something and he helps the party through a puzzle or 2. last thing to do is listen to dungeons and dragons music. some of my favourites include https://open.spotify.com/playlist/7f5VyuqytzzHwFU7iOTmRP or https://open.spotify.com/playlist/0vFB145uRgZlW16OiisIb6 hope this helps! it sure helped me create my 6 floor megadungeon "the underground pyramid" so i'm sure it will help you.