'Storage almost full' on the day of the shoot: what you can safely delete, in order

Storage warnings are the most actioned and least understood notification on the phone, and the standard response - download a cleaner - is the worst first move available. Cleaning a phone is a sequence, because the space that matters lives in places where deletion has consequences: chat media, camera originals, and the quiet tax every app pays in cache. Here is the order that frees gigabytes without losing a single thing that cannot be re-downloaded.

Before deleting anything: the two-line check

Open your storage screen (Settings - Storage, on both platforms) and read the breakdown, not the bar. Photos/videos at the top is a backup-then-offload job; "Other" or "System data" at the top is a cache-and-apps job; a single huge app is its own project. And one law that no app tells you: a phone needs roughly ten percent free to do its background work - updates, messaging, camera speed. Filling to the last megabyte is why "cleaned" phones still feel fatigued.

The safe list, most gigabytes per minute first

• Video, oldest first: the camera roll's big files are usually ten clips, not a thousand photos. Delete what you have already sent or posted, and for the rest - one backup to drive, verify it opened, then delete on-device with the sync check below.
• WhatsApp's media folder: the single largest hoarder on Nigerian phones. The in-app storage manager (Settings - Storage and Data - Manage Storage) lists chats by size and - this is the part the folder in a file manager does not give you - shows which chat each file came from, so you delete the memes, not the receipts. Then turn off auto-save for the noise groups, because otherwise this job recurs monthly.
• Offload, do not delete: on iOS "Offload App" keeps the documents and drops the binary; on Android the equivalent is uninstalling the rarely-used apps that hold no data. Twenty games you open twice a month are two gigabytes of "maybe I'll need it".
• Streaming downloads: every music app and Netflix keeps the offline shelf - re-downloadable in minutes on good wifi, invisible to galleries, and usually a full gigabyte sitting at "just in case".
• Caches, last: per-app cache clears (Android's Storage screen) or offload-reinstall for the iOS hoarder - useful, bounded, and the ONLY job a "cleaner" was doing. You did not need the cleaner; you needed the screen that lists apps by size.

The one dangerous deletion

Deleting photos from the gallery while cloud backup is on - without checking where "delete" actually reaches - is how "freeing space" becomes losing the christening video. On iCloud with sync enabled, gallery deletion is library deletion. Back up first, verify off-device, then delete, and if the phone cannot answer "is my photo stored somewhere I can see?" the right move is to keep it on the phone and delete something else.