A boy who can't lift his arms or keeps tugging at a scratchy collar will look exactly like that in the picture. For family holiday photos, the shirts that work are the ones he'd happily wear to a relative's house anyway: boys polo shirts, soft button-downs and a few knit layers that add colour without adding stiffness.

Pick by the setting first. A living room by the tree, a park in late autumn and a portrait studio call for different weights, and the right choice usually sits one notch more relaxed than the adults' outfits.

Collared shirts that still let him move

A collar frames a face well in photos, which is why most parents reach for one. The trick is choosing a collar he won't fight.

Polo shirts

Boys polo shirts suit kids who live in T-shirts and protest anything with buttons down the front. The knit fabric stretches when he sits on the floor or gets hoisted onto a lap, and a short buttoned placket keeps the neckline tidy. Their limit is formality: next to a parent in a blazer, a polo can read as a golf outing. A long-sleeve polo in a deep colour looks more seasonal than a short-sleeve one in pastel. Check the collar before you buy: a thin knit collar tends to curl at the tips after a few washes, while a firmer ribbed one holds its shape on camera.

Soft button-down shirts

Boys button-down shirts give the most polished look and pair easily with sweaters and vests. Choose oxford cloth, chambray or a washed poplin; these feel softer than a crisp dress shirt and don't have its sheen. The limit is fit around the chest and neck: a shirt that pulls between buttons gapes in every seated pose. Check that he can button the collar and still slide a finger inside, or plan to leave the top button open, which looks natural on younger boys anyway.

Flannel shirts

A soft flannel in a muted plaid works well for outdoor sessions, tree farms and cabin settings. It's warm and forgiving of wrinkles. Its limit is pattern: big plaids compete with everyone else's outfits, so let one person wear the plaid and keep the rest of the family in solids that pick up its colours. Check that the plaid isn't tiny; very fine checks and narrow stripes can produce a wavy shimmer, called moiré, in digital photos.

Henleys

A henley, a collarless knit pullover with a short buttoned placket, suits boys who refuse collars outright. It looks more finished than a T-shirt and layers well under an open flannel or cardigan. The limit is that a thin henley clings and shows every wrinkle, so look for a heavier waffle or slub knit. Check the sleeve length: knit sleeves that stop above the wrist bone look short in photos, especially when he holds a sibling or a gift.

Knit layers for colder or dressier photos

A jumper over a collar is the easiest way to look dressed up without a tie, and it hides a shirt that's already lost its press.

Crew-neck jumper over a collared shirt

This combination suits school-age boys in formal portraits or church settings. Let the collar sit outside the neckline and the cuffs show just slightly at the wrist. The limit is heat: indoor sessions under lights get warm, and an overheated kid stops smiling fast. Check the knit for itch by rubbing it on your inner wrist; cotton and cotton blends are usually gentler than wool for kids who notice scratchy fabric.

Quarter-zip pullover

A quarter-zip suits tweens and teens who want to look like the older relatives without wearing a dress shirt. It layers over a polo or T-shirt and zips higher for cold outdoor shoots. The limit is the zipper itself, which can pull open unevenly as he moves. Check that it lies flat when zipped partway; a stiff zipper tape puckers and looks crooked in close-ups.

Cardigan

A cardigan works well for toddlers and young boys because nothing passes over the head, so his hair stays the way it was combed. Over a button-down or henley it looks classic, and a shawl collar adds a little dressiness. The limit is bulk: a thick cardigan can make a small child look swallowed. Check that the buttons line up after he sits down, since a cardigan buttoned one hole off is easy to miss during the session.

Checks that apply to every shirt

Have him wear the full outfit for twenty minutes at home a few days before the session. Anything that bothers him in the kitchen will bother him more in front of a camera, and you'll spot wrinkles, gaps and a riding-up hem while there's still time to swap.

While he has it on, run through the checks that show up on camera:

• He can raise both arms without the hem untucking or the shoulders pulling.
• Buttons and collar don't strain when he sits on the floor or on a lap.
• The colour is a rich tone such as navy, forest green, burgundy or heather grey; bright white and neon can lose detail in strong light.
• Large logos and printed words are absent, since they pull the eye away from faces.
• Tags and inside seams don't scratch; cut tags out or choose tagless shirts for sensitive kids.

Coordinate rather than match. Choose two or three colours for the family and let each person wear them differently; identical outfits tend to look staged, which is the stiffness you're trying to avoid.

Get the shirt ready the day before

Wash a new shirt once ahead of time so you know how it fits after washing and the package creases are gone, then hang it up right away. Steam or iron the collar and placket the night before, since those are what the camera sees most. For younger kids, pack a backup top in the same colours so a spill of hot chocolate doesn't end the session.