The anchors that came in the box are why the shelf fell

Quick answer: Set the clutch low and work up, drill a pilot hole the size of the screw's core, and find a stud before you reach for any anchor. When you do need one, throw out the little plastic ones packed with the shelf and buy a real toggle.

There's a mirror leaning against a hallway wall somewhere right now. It's been there since spring. It's heavy, it's nice, and everybody in the house walks past it every morning, because hanging it means the drill, and the drill means a hole you might get wrong.

You won't get it wrong. A drill is a simple machine with two settings that matter and one decision, the anchor, that people get wrong constantly. Learn those and the mirror's up by lunch.

Buy a drill/driver, not a kit with nine gadgets

For a house, you want a cordless drill/driver. That's the standard pistol-grip drill with an adjustable clutch. It drills holes and drives screws, and that covers almost everything you'll do.

A 12-volt drill is lighter, smaller and plenty for shelves, curtain rods, furniture and cabinet hardware. An 18- or 20-volt drill is heavier and stronger, and it's the better pick if you'll be building a deck or drilling into brick. Most people living in a house with drywall walls are happier with the 12-volt. It doesn't wear out your wrist overhead.

What I'd buy: a brushless drill/driver from a line you can grow into. Milwaukee M12, DeWalt 12V MAX, or Ryobi ONE+ if you want one battery for a whole shelf of tools. Two batteries if the kit offers it. A dead battery halfway through a curtain rod is how a twenty-minute job becomes a Saturday.

What I'd skip: the bargain no-name kit with a 100-piece bit set. The bits are soft, the battery fades, and the chuck wobbles. Also skip the impact driver for now. It's a great tool for long screws in lumber, but it has no clutch and it'll happily snap a small screw or blow straight through drywall.

The clutch is the whole trick

That numbered ring behind the chuck is the clutch. It decides how hard the drill twists before it gives up and starts clicking.

Low numbers slip early. High numbers push harder. The little drill-bit icon at the end means no clutch at all, full force, which is what you want when you're making a hole and not what you want when you're driving a screw.

When you're driving screws, start around 5 or 6. If the drill clicks before the screw is snug, turn it up one notch and try again. When it clicks right as the head sits flush, you've found the setting for that screw in that material. The clutch exists so you don't strip the head, sink the screw too deep, or crack the board. Use it.

There's also a speed switch on top, usually marked 1 and 2. Gear 1 is for driving screws. Slow and strong. Gear 2 is for drilling holes. Fast. People leave it in 2 forever and then wonder why every screw head turns to mush.

Drilling a clean hole

Most wood screws want a pilot hole. Skip it and the wood splits, especially near an edge or in hardwood.

To size the bit, hold it in front of the screw. You should see the threads sticking out on both sides but not the solid core of the screw. If the bit hides the threads, it's too big and the screw won't bite.

Then:

• Wear safety glasses. Drywall dust in an eye ends the afternoon.
• Mark your spot with a pencil cross, not a dot. A dot disappears under the bit.
• Wrap a flag of painter's tape around the bit at the depth you want. Stop when the tape touches the wall.
• Hold the drill square to the surface. Look at it from the side once before you pull the trigger.
• Start slow so the tip doesn't wander, then speed up. Let the bit do the work. Leaning on it doesn't help.
• In anything deeper than an inch, back out partway once or twice to clear the shavings.

For tile, put a strip of tape over the spot so the bit doesn't skate, and use a bit made for tile. For brick or concrete, you need a masonry bit and the hammer setting, which a 12-volt drill usually doesn't have. That's the job the bigger drill is for.

Driving a screw without stripping it

A stripped screw head almost always comes from the bit climbing out of the slot. That's called cam-out, and the fix is pressure. Push in firmly, in line with the screw, and run it slow.

Match the bit to the head. Most household screws are Phillips #2. If you're choosing screws yourself, square-drive or Torx heads grip far better and barely strip at all. Buy those when you get the choice.

Stop just as the head goes flush. One extra second and you've crushed the wood fibers or punched through the drywall paper, and that screw is done holding anything.

Before you put a hole in a wall

Find the stud. It's the best anchor there is, and it's free.

In most houses, studs run vertically every 16 inches, measured center to center. Sometimes 24. A stud finder will show you the edges. Mark both, then aim for the middle. To confirm, push a thin finishing nail through the drywall where the mirror will cover it. You'll feel solid wood or you'll feel nothing.

Wiring is the part that should actually slow you down. Don't drill directly above or below an outlet or switch, because wires run up and down from them along the studs. A stud finder with an AC-detection mode helps. If a spot makes you uneasy, move a couple of inches and use a toggle instead. In a house with old plaster and lath, drill slowly with a sharp bit, and have an electrician look at anything that seems off.

Anchors, from best to worst

When there's no stud where you need it, you need an anchor. This is the decision almost everybody gets wrong, mostly because the shelf came with a little bag of plastic ones and they figured the manufacturer knew best.

The manufacturer was saving money.

1. A stud. Always first, whenever the layout allows it.

2. Toggle bolts. For heavy things in drywall: mirrors, floating shelves, a TV mount when the studs won't line up. The Toggler SnapToggle is the one I'd buy. You drill a half-inch hole, slide in a metal channel that flips flat behind the drywall, snap off the plastic straps, and it grips a broad patch of wall from behind. The hole is big, and that's the price. It's also why it holds.

3. Self-drilling threaded anchors. E-Z Ancor and similar. You screw them straight into the drywall with a Phillips bit, no pilot hole, then drive your screw into them. Good for medium loads: towel bars, small shelves, framed art. Drive them slow, on gear 1, or they spin and chew out the hole.

4. Plastic expansion anchors. The ones from the bag. Fine for a light picture or a smoke detector. Not for anything you lean on, hang a coat from, or put dishes on.

Every anchor package lists a weight rating. Those numbers come from ideal conditions: new drywall, a perfect hole, a load pulling straight down. Your towel bar gets yanked sideways every morning. Leave yourself a wide margin, use more than one anchor, and when you're torn between two sizes, go bigger.

For the mirror: one screw into a stud if one lines up, and a SnapToggle on the other side. Level it before you mark the second hole, not after.

If the drill was borrowed

Bring it back with the battery charged, every bit back in its slot, and a box of good screws or a new bit set tucked in the case. That's how you get asked to borrow it again.

Then buy your own. Something happens to you the first time you hang a heavy mirror alone, step back, and push on the frame and it doesn't move. It's the same steadiness you bring to the raise conversation when you've done the homework: you stop hoping it'll hold and start knowing why it does.

The hallway's been waiting since spring. Go find the stud.