The first photo of an item is a snapshot. The tenth is a record. Somewhere between the two, the question changes from what the thing looks like to what the photo can prove.
The camera roll sorts your photos by date rather than by item, and you took those shots to show something off. That is the wrong order for a record. The questions a collection photo gets asked arrive later, from a buyer, an insurer or your own memory: which variant is this, is that mark a printing flaw or damage, was the corner soft when it arrived. Long after the listing has gone, the photo is the only witness.
What the photo has to prove
Before you press the shutter, name the question this frame answers in three years. The front of a mint card in good light answers what it is, and not much else. Add the back and you cover the printing marks. Add the corner in close-up and you have a condition record with a date on it.
Photograph the item when it arrives, before it goes into a sleeve, a box or a shelf. Damage picked up later is easy to argue about when there is a photo from the day it landed.
One slot or ten
Images live on the item rather than in its fields, so they take up no room in the schema. Your plan decides the count: one image with a 5MB ceiling on Free, ten with a 10MB ceiling on Pro.
On a single slot, take the front. It is the image the card in the grid will show, so it does the work of identifying the item in a list. On ten slots, spend them in the order below.
The four shots
The whole item, front on
Square to the camera, against something plain. A sheet of paper, a placemat or the back of a poster makes a better background than a styled set-up, because the reader is looking at the edges of the item and not at the props.
The other side
Variants hide on the back: printing marks, publisher logos, a barcode, a serial number. If the item is sealed or slabbed, photograph the label on the case as well as the thing inside it.
The flaw, in close-up
Get close enough to show where the damage starts and stops, and leave some undamaged surface in the frame so a stranger can judge the size of it. A ruler or a coin beside the mark does that for you.
The label or serial
Anything carrying letters or numbers you would otherwise retype: the printing code, the certificate number, the signature, the maker's stamp. A wrong digit typed into a field is invisible; a photo of the label settles the question.
Where phone photos go wrong
Glossy stock, a plastic sleeve and a sealed box reflect the light in the room. Stepping closer to the item makes the reflection larger, so change the angle between the light and the item rather than the distance to the lens. A flash fired straight at the surface returns a white disc in the middle of the frame, and an indoor bulb tints whatever it lights: a white card under a warm bulb reads as cream to a buyer comparing two photos of the same item. The file format matters as well. An iPhone left on its default HEIC setting sends a file collectd will not accept, and the fix sits in the camera settings: Formats, then Most Compatible.
Compose for the crop
The item card shows its cover image in a 4:3 frame and fills that frame, so the photo is cropped to fit. A tall poster loses its top and bottom in the grid, and a wide shot of a keyboard loses its ends. Shoot with margin around the item, keep anything you care about away from the outer edge, and check the result at thumbnail size, because the same file appears large on the item page and small on the card. A detail that stops being legible at card size has earned its own photo.
Say what the photo cannot
Each image takes a caption of up to 200 characters, and the caption sits over the image. Use it for what the pixels cannot carry: where the item came from, what you paid, what the seller told you, what is missing from the box. Write the caption while you are shooting. The event, the seller and the price are the three details you lose first.
Four shots to start
Take the front, the back, the flaw and the label as the item arrives. That set answers the questions a single photo cannot, and it takes about a minute. Anything else is a bonus.
The mechanics of the collection these photos sit in are covered in two guides: the first-collection guide walks through setting one up, and the fields guide covers the field types. If you are still deciding what to record, Anatomy of a collection schema works through the six fields worth having before a collection gets large.