Start by reviewing what is taking up space, not by deleting the biggest thing you can find. Decide what you need to keep and confirm that important files have a usable backup before making changes.
Separate looking from deleting.
Storage tools can group items such as apps, documents, pictures, and temporary files. Treat the list as information, not a recommendation to remove everything in a category. A Downloads folder can contain files you still need.
Choose one group to review.
Start with something you recognize. Open the list, identify the files, and leave unfamiliar items alone. Do not remove system folders or use a cleaner you found through an alarming popup.
Be clear about copies.
Before moving or removing an important file, know where the version you intend to keep is stored. Open a few important files from the backup location to check that you can use them. If you do not understand how a cloud folder works, check the provider’s instructions before deleting from it.
Read the final confirmation.
Look for exactly which files will be removed and whether recovery is possible. Emptying a recycle or trash folder is a separate decision. Do not assume every cleanup can be undone.
A useful stopping point.
It is fine to stop after learning what uses the space. You do not have to complete a cleanup in the same sitting. Ask for help before removing items you cannot identify.