Basic adjustments that help.
WHAT TO DO
Crop to remove distraction and improve framing Straighten, since a tilted horizon is noticeable Adjust brightness and contrast if the image is flat Correct colour if it is obviously wrong
WHAT NOT TO DO
Heavy filters, which date quickly and look amateurish Over-saturating, which makes products look unrealistic and produces returns Excessive editing of people
CONSISTENCY
Apply similar adjustments across a set, so a product catalogue or a team page looks coherent.
RESIZING
To the dimensions actually needed. Around 1200 pixels on the longest side for most content images.
COMPRESSING
After resizing. An optimisation tool or plugin handles this.
TOOLS
A phone's built-in editor is adequate for cropping and basic adjustment.
Free online tools handle resizing and compression.
FILE NAMES
Rename before uploading: blue-cotton-shirt.jpg rather than IMG_4471.jpg. It helps search and helps you find things later.
THE ORDER
Edit, crop, resize, compress, rename, upload.