I don’t have a specific video recommendation handy, but I’m sure if you punch “how to safely clear a [pistol/revolver/rifle/shotgun]” into YouTube you’ll get 10,000 good results.

As a general overview though (and bear in mind that there’s countless models of firearms out there, so there’s bound to be some outliers that don’t quite fit into this.)

Step 0. Make sure you are keeping the muzzle pointed in a safe direction and your finger off the trigger at all times.

Step 1. If there’s a removable magazine, remove it.

Step 2. Pull back the slide/cocking handle/bolt/pump/lever, if there’s a round in the chamber, this should eject it. There’s an important reason to do this after removing the magazine, because releasing that mechanism will load the next round from the magazine there is one in there.

Step 3. Repeat that at least 1 more time to make extra sure that another round didn’t get loaded. Keep going until no round ejects. For some guns where the magazine isn’t removable, like some pump action shotguns, it can sometimes be quicker or more convenient to do that repeatedly than to remove the rounds manually.

Step 4. Lock open the action of the firearm and visually confirm that there is no round in the chamber and nothing in the magazine well.

Step 1R. (if you are clearing a Revolver.) Release the cylinder

Step 2R. Press the ejector rod to eject the rounds.

Step 3R. Visually confirm that all of the rounds have ejected.