1. Wipe the lens. Yes, right now.
Your phone lives in your pocket, rubbing against fabric and dust all day. Before you shoot, wipe the lens with the hem of your shirt. One quick wipe removes the haze that makes 90% of "why does this look foggy" photos foggy. This is the single highest-return action on this list: it takes two seconds and no skill.
2. Turn on the grid lines
Every phone camera has a 3×3 grid overlay. Find it (Settings → Camera → Grid on iPhone; Camera Settings → Grid lines on most Android phones) and leave it on forever. The grid is how you stop guessing where things are in the frame. Rules 3, 4, and 5 below all depend on it. Composition is a visual skill, and the grid is training wheels that never come off — professionals use viewfinder grids too.
3. Keep the horizon level
A tilted horizon makes the viewer feel slightly seasick, even if they can't say why. Use one of the grid's horizontal lines (or the water line, or a distant building edge) and align it with the actual horizon. If your phone shows a level indicator, center it. A crooked horizon is the fastest way to make a decent photo look amateur, and it's a two-second fix.
4. Put the face on an intersection point
With the grid on, stop centering the face. Put it near one of the four points where the grid lines cross — usually the upper-right or upper-left one. Centered subjects look like ID photos. Off-center subjects look like photographs. This is the rule of thirds in one sentence, and it's the difference between "he took a photo of me" and "he knows what he's doing."
5. Leave space toward the gaze
If she's looking left, put more empty space on the left side of the frame. If she's walking right, she needs room on the right to "walk into." Space behind the subject (away from where they're looking) is dead space; space in front of the gaze is story. This one rule alone makes candids look dramatically better.
6. Never crop at the joints
Don't cut the frame at the neck, wrist, elbow, knee, or ankle. A crop at a joint makes the limb look amputated — viewers feel it as wrong even if they can't name it. Instead, crop between joints: mid-thigh, mid-forearm, mid-shin. Better yet, zoom out and give the body some air. This is the mistake that gets most "ew, why does this look weird" reactions.
7. Subtract background clutter
Before you tap the shutter, spend three seconds looking at everything behind her: trash cans, signposts, strangers' heads, a pole growing out of her skull. Move half a step left or right, or take two steps back so you can blur it out. A clean background is worth more than any filter. If you can't move, shoot wider and crop later — it's easier to cut clutter out of a big frame than to fix it in a tight one.
8. Light matters more than filters
No filter fixes bad light. The rules: never shoot with the sun (or the brightest light) directly behind her unless you want a silhouette; get the light hitting her face at an angle — window light from the side is the best free portrait light in existence. Outdoors, overcast days are a gift: clouds are a giant softbox. And when the light is bad, don't fight it — shoot the silhouette and call it art.
9. Burst-shoot, then pick the best
People blink, hair moves, expressions change in half a second. Hold the shutter down and take ten frames instead of one, then delete the duds. This is what every event photographer does; it's not cheating, it's the job. The candid she loves is almost always frame seven, not frame one.
10. Check the shot immediately
After you shoot, look at the photo on the big screen before you move on. Is it sharp? Is the horizon level? Did you crop at a knee? If something's wrong, you still have her, the light, and the moment — reshoot now, not later. Checking takes five seconds and saves you from discovering at midnight that every photo from the day has a tilted horizon.