I suck at drawing maps and dungeons. Fortunately, there are plenty of resources out there for random dungeons. My current project is using the geomorphs from Dave's Mapper to generate the dungeon levels which are 300' x 300'. I then tweak the maps, key them and add any symbols such as stairs and traps using Photoshop. I then use the random stocking tables from the AD&D DMG, then import the map to a One Page Dungeon template and then type in the room details such monsters, treasures etc.,
I like the random method, because if I can suffer from mental paralysis trying to plan out a dungeon to make it "make sense". The random method can create it's own little stories. For example I have one room where there are 8 Volts (Fiend Folio) and an adjacent room of 6 Troglodytes with a treasure in a small 10' x20' room. What I have determined here is that the Trogs are a scoting party that got suprised by the Volts who killed several of their party and have them trapped in that room. I have added to the room description the bodies of several dead troglodytes. The Volts are trying to get into the room to eat the them and so will be automatically suprised if the PC's enter them room. If the PCs deal with the Volts, the Trogs will negotiate with the PCs a peaceful exit in exchange for the treasure they found while trapped.
There is one Level where I rolled way above average for the amount of empty rooms. I later rolled a Gelatinous Cube on that level. So, now there is a logical reason for the emptiness of the level. The Cube ate mostly everyone there!. I'll have to make note of clear slime trails throughout the level as a clue.
The one thing I did plan though was the placement of several privys throughout all the levels. Whoever built and lived in the dungeon way back when needed to relieve themselves somewhere, so I made most of all the 10' x 10' rooms the latrines. I'll have to make sure to place an Otyugh in one of them.