Fog of war on maps

For those of you who make your own maps. How do you manage fog of war to keep the element of discovery? Especially on large maps.  My group is playing tomorrow and I don't want to reveal the entire dungeon since it is quite large. 

1. VTT
2. draw it on a vinyl battle map
3. print it and cover with sheets of paper held down using painters tape (circular cutouts of different sizes work particularly well)
4. print it and cut it up. Lay down sections as you reveal. Maybe hold in place with painters tape.
5. approximate with tiles or 2-1/2D
6. Theatre of the mind
7. Theatre of the mind, but with dramatic pictures for each scene or room
8. ...