Accept some risks
Dungeons are dangerous. They’re full of weird and unexplained things, and most of them are trying to kill you. It pays to be cautious, to take your time, and to consider your options carefully before you commit to an action. Smart players don’t take risks unless they have a reasonable belief that there’s some potential benefit.
But there’s another risk in dungeons, one that new players fall into over and over again. Faced with a dungeon full of dangers, they refuse to commit to any course of action. This goes one of two ways. Either the session ends with a tired, dispirited party, resources sapped by random encounters, no richer or wiser than when they started. Or worse, people get tired, people get bored, and someone decides to commit to any action at all, just to make something happen. Often as not this leads to disaster.
So accept that there’s likely no risk-free option. Whatever you do is going to carry the potential for death and dismemberment. Find ways to minimise that risk. Send in a first-level character. Keep the rest of the party clear. Get your hirelings in position first. Have the wizard do some research, or cast a spell. But when it comes to it, roll the dice and accept the outcome.