When taking a picture, there are 100 things to consider: aperture, shutter speed, ISO, white balance, lens flare, and on and on, right down to that guy waaaaay in the back of the frame who is making an obscene gesture. Trouble is, if you think about all of these elements, chances are that before you press the shutter, the moment-if not the hour-will have passed.

With enough practice, getting the shot and the various factors right becomes instinctual and almost instantaneous. But until you reach that level, what do you really have to know to get the picture? That’s the question the Pop Photo team and I tackled recently: In common situations, what’s the single tip you must remember when the other 99 things have slipped your mind?

Here’s some one-trick help:

Candid Portraits. If you’re photographing a subject who is talking, shoot in burst mode; you’re sure to get one with a closed (or at least attractive) mouth.

Headshots. Step back and use at least an 80mm (equivalent) lens. The long lens compresses perspective and keeps your subject’s nose from appearing too big.

Lush Landscapes. Put a circular polarizing filter on your lens. It will make the greens greener and the sky bluer. And the rotating filter lets you dial in as much or as little as you need.

Parties. Keep your subjects away from walls. This way, there’s no shadow behind them. Instead, direct them into the middle of the room where you can capture some of the ambience of the event. And the flash? Bounce it off the ceiling.

Beating RedEye. Don’t count on your camera’s preflash or redeye reduction. Instead, get the flash as far from the lens (“off-axis”) as possible. Wireless flash is great for this.

Dancers. Partygoers waltzing? Set your flash to slow-sync (even point-and-shoots have this function). This gives you a slow shutter speed, so there’s some blur for a sense of motion, but a burst of light that captures the subjects sharply and clearly. It’s even better if you use trailing sync, which puts the blur behind the flashed image.

Sports. Don’t focus where the action is; focus where it will be. Whether it’s a racecar or a base runner, prefocus ahead of your subject and hold the focus there by pressing the shutter button halfway down.

Weddings. When the clothes are traditional (bride in white, groom in black), where do you turn for a good exposure reading? Meter off a gray card. No 18% gray handy? Get really close, take a reading off the bride’s skin, then back up and shoot.

Big Family Dinners. Use the widest lens you have, get on a stepladder, and bounce the flash off the ceiling.

Food. Shoot down onto the plate. Chances are the chef put the dish together from that point of view for the best angle.

Sunsets. Forget the sunset itself! You’ve seen that shot before. Turn around-the rich sunset light on buildings, its reflections on clouds, and the shadows it creates are much more interesting.

Ask John:

Q: What’s the thinking behind making f-stop values in reverse order to the lens opening sizes?

A: F-stops are the ratio of focal length divided by the diameter of the physical opening of the aperture. So a small opening and/or long focal length makes a bigger number; a big opening and/or short focal length makes a smaller number.