Dungeon exploration procedure

 While D&D combat has a pretty clear order of operations and economy of actions, outside of combat I've tended to play things fast-and-loose regarding sequence, timing, and number of actions. I wouldn't be at all surprised if many other DMs handle things similarly. There's nothing inherently wrong flying by the seat of your pants, if that works for you, but if timekeeping becomes a tangled mess and/or you have some very assertive players who tend to monopolize the game between combats while passive ones barely get a chance to participate, a more structured exploration sequence may help. The editions I've played (B/X and BECMI, mostly) do give some guidelines, but for most of my DMing career I've struggled with how to apply them. Below is a more detailed, but still hopefully simple, step-by-step procedure for dungeon crawling.

1. Party moves, either until its exploration movement rate is exhausted or a keyed location or other point of interest is reached. 

2. Describe what the characters can readily see, hear, smell, and/or feel from where they stand. This should be in general terms and broad impressions, just enough detail to allow players to make informed decisions about how to interact with the contents of the location. If the turn's movement in step 1 has not brought the party to a keyed location or other point of interest, this may be just a brief description of the paths open for the next turn's movement.   

3. Interaction. Give the players a moment to discuss and decide what they want to do, as a group and individually, and then either have a caller report each one's choice, or ask each player directly what his/her character is going to do. This may include listening at a door or searching for traps, negotiating with any monsters encountered, searching or examining features of the location, standing guard, and so on.* If movement (step 1, above) ended without reaching a point of interest, or if the party wishes to pass by such a point and it's possible to do so, proceed to step 4, then skip to step 6 before continuing.

    3b. If the party remains longer than one turn, reveal details in layers each subsequent turn until they have either exhausted the area's contents or decide to move on without turning every stone. For example, if a cluttered desk is observed in step 2, a player may announce searching the clutter on top during the first turn, finding nothing of interest. In the second turn, he chooses to rifle through its drawers, finding a lockbox. In the next turn, the PC pries the box open and discovers a journal, and then takes a fourth turn to skim the journal for useful information. 

4. Roll for random encounters. If one is indicated, it occurs before (and instead of) the resolution phases in step 6. If one or more characters chose to stand guard in the direction from which the encounter comes, reward the group with reduced or no chance to be surprised. If encounter check is negative, go to step 6. 

5. Resolve each character action in whatever order seems logical. Provide whatever new information the character would gain from his or her action. A player may be eager to immediately follow up on whatever he discovers, but except for requests for clarification and very simple actions requiring only a moment, it's better to move on to the next character and leave follow-up actions for the next turn.** For instance, if a player says his character will search the clutter in a dark corner, and he finds a treasure chest there, it's reasonable to allow him to open it if it isn't locked and get a glimpse of whatever is inside in the same turn, but not to search it for traps, try to pick the lock, or dig through the contents. The goal here is to allow each player his or her own turn in the spotlight, rather than letting an assertive or overenthusiastic player press on ahead and take more actions at the expense of the more passive ones. If someone's action leads to an urgent situation (e.g. a trap is triggered or a monster is summoned or some such) it may make sense to permit characters whose actions haven't yet been resolved to drop them and do something else.

6. Mark off a turn using whatever time tracking method you prefer, note remaining durations of spells, light sources, and other effects, and apply results if any durations expire. 

7. If the party remains in this area, repeat steps 3 through 6 as many times as needed until the party decides to move on.

8. Return to step 1.

*Sometimes, it's normal that only one character takes an action for the turn, while the others are idle. For example, when the party comes to a door at the end of a corridor, it would usually be unwise for the other characters to go off doing their own things while the thief searches it for traps. In this case, the other party members can be considered to be on watch for trouble, and the thief's action should be resolved as quickly as possible to avoid bogging down the adventure. 

**In general, for simplicity and consistency, actions that take more than a brief moment should be considered to take a full turn. Searching a 10' square area, a 10' section of wall or shelf, checking an object for traps, disarming a trap, skimming a book, securing a door with iron spikes, or prying gemstones out of a statue or bas relief should all take about a turn. Snatching up a clearly visible item, opening an unlocked door or chest, reading a brief inscription in a language a character knows, or setting off an obvious trap with a 10' pole might take only a few seconds, and not count in any appreciable way toward the next turn.